Shutter operating mechanism for magneto-optical disk drive

ABSTRACT

A magneto-optical disk drive incorporates: a structure to mount a front panel to a frame using a cartridge loading system, using a set of linearly movable control cam plates, to draw a cartridge into a cartridge holder and then to move the cartridge holder to an operating position; a timing control system for the cartridge loading system, which includes a unitary encoder cam gear including a drive gear portion to move the cam plates to lift and lower the cartridge holder, a cam groove portion to draw a cartridge into the cartridge holder, and timing encoders portions to interrupt photo sensors; a shutter mechanism to fully close a cartridge slot with a shutter, both when the drive holds a cartridge and when empty; a magnetic head vertical positioning system to position a magnet head base against fixed reference surfaces below and a set of resilient members above; a magnetic head horizontal positioning system to first fix the magnetic head base to rotate horizontally about a point, and then to resiliently hold the case from rotating against a rigid member; a magnetic head carriage lock mechanism to hold a magnetic head carriage in its outermost radial position; and a control system for quickly synchronizing magnetic head movement and optical head movement by first moving both heads to an outermost radial position.

BACKGROUND OF THE INVENTION

The present invention relates to magneto-optical disk drives,specifically to systems for mechanical operations of a disk drive.Conventional systems for governing the operation of a magneto-optical(MO) disk drive, including systems for insertion of disk-bearingcartridges, applying a magnetic head, and allowing access to theinterior of the disk drive, require many sensors and switches andcomplicated control circuits and routines. These systems are typicallydifficult to synchronize, and difficult to immobilize duringtransportation of the disk drive. If a mechanism such as a spring-loadedcartridge insertion and ejection mechanism is used, the operation istypically unstable and may jar the precision alignment of the internalreading and writing mechanisms. When moving parts are moved intoposition, misalignment and unstable positioning is an additionalproblem.

Furthermore, although shutters covering a cartridge insertion slot arewell-known, where the body of an inserted disk cartridge is used topartially block dust or dirt from the MO disk drive interior, suchshutters are unable to completely block the cartridge insertion slot,leaving the disk cartridge and sensitive optical components of the diskdrive exposed to dust and dirt.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an improvedshutter operating mechanism that enables a shutter plate to be easilymoved in synchronization with cartridge loading operations to closedpositions both when a disk drive holds and is empty of a disk cartridge,and to a fully retracted position when a cartridge is being inserted.

It is another object of the present invention to provide a diskcartridge loading system for a disk drive that draws a cartridge into acartridge holder and moves the cartridge holder into a reading/writingposition, using very few sensors and parts and in a single, smoothmotion.

It is still another object of the present invention to provide a timingcontrol system for a disk drive that is capable of moving both a diskcartridge holder and a magnetic head between various operating positionsusing a simple control with few sensors and few parts.

It is yet another object of the present invention to provide a verticalpositioning system and a horizontal positioning system for a magnetichead base which will securely hold the magnetic head base in a stableposition against reference surfaces.

It is yet still another object of the present invention to provide amagnetic head carriage locking mechanism which can hold a magnetic headcarriage in a secure position when the magnetic head base is away from awriting position.

It is a further object of the present invention to provide a controlprocess and apparatus to pre-align a magnetic head and an optical headbefore the heads are synchronized to each other.

According to one aspect of the present invention, a shutter operatingmechanism (for a shutter for a disk cartridge insertion opening of adisk drive) comprises a shutter plate, the shutter plate having a closedposition and a retracted position, the closed position fully closing thecartridge insertion opening, and the retracted position being completelyretracted from a loading path of an inserted cartridge. The shutteroperating mechanism further comprises a means for moving the shutterplate, the means for moving having first, second, and third distinctpositions. When the means moves to the first position, the shutter platemoves to the closed position, and when the means for moving moves to thesecond position, the shutter plate moves to the retracted position, andwhen the means for moving moves to the third position, the shutter platemoves to the closed position.

According to another aspect of the present invention, a disk cartridgeloading system for a disk drive comprises a disk cartridge holder, meansfor guiding the disk cartridge holder, a drawing mechanism to draw adisk cartridge into the cartridge holder (the drawing mechanism having ahooking position and a drawn-in position, and hooking a partiallyinserted disk cartridge at the hooking position and drawing the diskcartridge fully into the disk cartridge holder at the drawn-inposition), means for guiding the drawing mechanism, to guide the drawingmechanism between the hooking and drawn-in positions; a drivingmechanism to drive both of (a) the guiding means for the disk cartridgeholder and (b) the guiding means for the drawing mechanism, an insertionsensor for detecting an insertion of a disk cartridge into the diskcartridge holder, and at least one position sensor to detect aoperational position of the driving mechanism. The driving mechanism isresponsive to the detection by the position sensor and to the detectionby the insertion sensor.

According to yet another aspect of the present invention, a timingcontrol system for a magneto-optical disk drive comprises a magnetichead base supporting a linearly movable magnetic head (the magnetic headbase movable between at least two magnetic head base positions), a diskcartridge holder holding a magneto-optical disk (the disk cartridgeholder movable between at least two disk cartridge holder positions), afirst guiding means (for guiding the magnetic head base to move betweenthe magnetic head base positions when the first guiding means isdriven), a second guiding means (for guiding the disk cartridge holderto move between the disk cartridge holder positions when the secondguiding means is driven), a motor, a plurality of sensors, and a timingcontrol member driven by the motor (the timing control member unitarilyincluding (a) a driving mechanism for driving the first and secondguiding means, and (b) a plurality of activators to activate thesensors). The motor drives the timing control member in response to theactuation of the sensors by the activators of the timing control member,and the driving means of the timing control member further drives thefirst and second guiding means to move the disk cartridge holder and themagnetic head base.

According to still another aspect of the present invention, a verticalpositioning system for a magnetic head base of a magneto-optical diskdrive (the magnetic head base supporting a linearly movable magnetichead) comprises a housing, a vertical reference surface member providedto the housing, a positioning member provided to the magnetic head base,a guiding member, contacting the positioning member, for moving themagnetic head base towards the vertical reference surface member, and aresilient biasing member provided to the guiding member, to bias themagnetic head base towards the vertical reference surface member. Theguiding member moves the positioning member of the magnetic head basetowards the vertical reference surface until the positioning membercontacts the vertical reference surface member, whereupon the resilientbiasing member contacts the positioning means and the guiding meansreleases the positioning means, and the positioning member is heldagainst the vertical reference surface by the resilient bias of thebiasing member.

According to yet still another aspect of the present invention, ahorizontal positioning system for a magnetic head base of amagneto-optical disk drive (the magnetic head base supporting a linearlymovably magnetic head) comprises a means for restricting motion of themagnetic head base to have a single rotational degree of freedom in ahorizontal plane when the magnetic head base is in a writing position;and a means of resiliently holding the magnetic head against a surfaceremote from the restricting means when the magnetic head is in thewriting position.

According to a further aspect of the present invention, a horizontalpositioning system for a magnetic head base of a magneto-optical diskdrive (the magnetic head base supporting a linearly movable magnetichead) comprises a sliding fit pin provided to the magnetic head base, asliding fit socket provided to a housing of the disk drive andhorizontally aligned to slidingly engage the sliding fit pin in awriting position of the magnetic head base, a loose fit pin provided tothe magnetic head base, a loose fit socket provided to the housing ofthe disk drive and horizontally aligned to engage the loose fit pin witha predetermined clearance in the writing position of the magnetic headbase, and a resilient biasing mechanism provided to the magnetic headbase (the biasing mechanism actuated when the magnetic head base is in awriting position). The engagement of the sliding fit pin and sliding fitsocket restricts the movement of the magnetic head base to rotationalmotion in a plane. The biasing mechanism resiliently pushes the loosefit pin against a wall of the loose fit socket when actuated, removingthe clearance and immobilizing the magnetic head base in a horizontalplane.

According to a still further aspect of the present invention, a magnetichead carriage locking system for a magneto-optical drive comprises adisk drive housing, a magnetic head base supporting a linear motor (thelinear motor further supporting a magnetic head carriage, the magnetichead carriage further supporting a magnetic head), an engaging memberprovided to the magnetic head carriage, and a resilient lockingmechanism provided to the housing of the disk drive, The resilientlocking member engages the engaging member, resiliently locking themagnetic head carriage against movement, when the magnetic head carriageis away from a writing position. Preferably, the magnetic head carriagelocking mechanism further comprises a controller, and the engagingmember is provided to an outermost portion of the magnetic head carriage(the outermost portion with reference to a motor hub of a spindle motorof the disk drive). In this case, the controller controls the linearmotor to move the disk magnetic head carriage to the outermost positionwhen the magnetic head base is away from a writing position.

According to a yet further aspect of the present invention, a controlprocess for synchronizing the movements of a magnetic head and anoptical head of a magneto-optical disk drive comprises the steps ofmoving the magnetic head to an outermost position with reference to amagneto-optical disk housed in the disk drive, then moving the opticalhead to an outermost position with reference to the magneto-opticaldisk, then detecting if a disk type is writable by means of the opticalhead, then determining if the magnetic head is to be applied to themagneto-optical disk based on the detection, and then synchronizinglinear positions of the magnetic head and the optical head if themagnetic head is to be applied to the magneto-optical disk.

According to a yet still further aspect of the present invention, acontrol system for synchronizing the movements of a magnetic head and aoptical head of a magneto-optical disk drive comprises a controller, amagnetic head carriage (the magnetic head carriage linearly movable andsupporting the magnetic head, the magnetic head carriage movable betweena standby position and a head application position, the standby positionbeing away from a magneto-optical disk held in the drive, and the headapplication position being proximate to the disk in order for themagnetic head to write to the disk), an optical head carriage (theoptical head carriage linearly movable and supporting the optical head,and the optical head able to read at least identification tracks of thedisk), and a means for synchronizing linear positions of the magnetichead carriage and the optical head carriage. The magnetic head carriageand the optical head carriage are moved to respective outermostpositions of the head carriages when the magnetic head carriage is inthe standby position and before the optical head reads theidentification tracks of the disk (the outermost positions being withrespect to a hub of a magneto-optical disk in the disk drive). Themagnetic head carriage is proximate to the outermost position of themagnetic head carriage, and the optical head carriage is at theoutermost position of the optical head carriage, when the synchronizingmeans synchronizes the linear positions of the head carriages.

DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 is a front view of an assembled MO disk drive according to theinvention.

FIG. 2 is a left side view of the assembled MO disk.

FIG. 3 is a rear view of the assembled MO disk drive.

FIG. 4 is a plan view of the assembled MO disk drive.

FIG. 5 is a top perspective view of an MO disk cartridge according tothe invention.

FIG. 6 is a bottom perspective view of the MO disk cartridge 42.

FIGS. 7(a) and 7(b) compose an exploded perspective view of the MO diskdrive.

FIG. 8 is a perspective view of a mounting base according to theinvention.

FIG. 9 is a frontal cross-section of the MO disk drive.

FIG. 10 is a side cross-section of the MO disk drive.

FIG. 11 is a frontal cross section of the MO disk drive, showing therelative locations of circuit boards and support members.

FIG. 12 is a schematic side view of a cartridge holder according to theinvention.

FIG. 13 is a partial plan view of the cartridge holder and a cartridgedraw-in mechanism according to the invention.

FIG. 14 is a bottom perspective view of a magnetic head base andmagnetic head assembly according to the invention.

FIG. 15 is a side view of an external side of a right control cam plateaccording to the invention.

FIG. 16 is a side view of an external side of a left control cam plateaccording to the invention.

FIG. 17 is a side view of an internal side of the right control camplate.

FIG. 18 is a side view of an internal side of the left control camplate.

FIG. 19 is a schematic of control cam groove profiles, showing themagnetic head base, cartridge holder, and shutter control cam grooveprofiles of the control cam plates.

FIG. 20 is a top perspective view of a loading chassis according to thepresent invention.

FIG. 21 is a left side view of an MO disk drive main frame, showing afront panel mounting structure.

FIG. 22 is a plan view of an MO disk drive main frame, showing the frontpanel mounting structure.

FIG. 23 is a left side cross-sectional view of an MO disk drive mainframe, showing the front panel mounting structure.

FIG. 24 is a left side view of an MO disk drive main frame, showing anassembly procedure for a front panel mounting structure.

FIG. 25 is a left side view of an MO disk drive main frame, showing asecond front panel mounting structure.

FIG. 26 is a detailed cross-sectional view of the second front panelmounting structure, showing an assembly procedure.

FIG. 27 is a detailed cross-sectional view of the assembled second frontpanel mounting structure.

FIG. 28 is a plan view of a drive system of an embodiment of a cartridgeloading system according to the invention.

FIG. 29 is a plan view of the drive system of FIG. 28, showing a firstlayer of parts removed.

FIG. 30 is a plan view of the drive system of FIG. 28, showing first andsecond layers of parts removed.

FIG. 31 is a plan view of the drive system of FIG. 28, showing first,second, and third layers of parts removed.

FIG. 32 is a cross-sectional front view of the drive system of FIG. 28.

FIG. 33 is a cross-sectional side view of the drive system of FIG. 28.

FIG. 34 is a partial side view of a control cam plate slidably mountedin the loading chassis.

FIG. 35 a bottom perspective view of a cartridge draw-in mechanism ofthe drive system of FIG. 28.

FIG. 36 is a plan view of the cartridge loading system, showing acartridge insertion position P1.

FIG. 37 is a plan view of the cartridge loading system, showing acartridge drawn-in position P2.

FIG. 38 is a plan view of the cartridge loading system, showing acartridge loaded position P3.

FIG. 39 is a plan view of the cartridge loading system, showing amagnetic head application position P4.

FIG. 40 is a plan view of the cartridge loading system, showing afail-safe return position P5.

FIG. 41 is a left side view of the cartridge loading system, showing thecartridge insertion position P1.

FIG. 42 is a right side view of the cartridge loading system, showingthe cartridge insertion position P1.

FIG. 43 is a left side view of the cartridge loading system, showing thecartridge drawn-in position P2.

FIG. 44 is a right side view of the cartridge loading system, showingthe cartridge drawn-in position P2.

FIG. 45 is a left side view of the cartridge loading system, showing thecartridge loaded position P3.

FIG. 46 is a right side view of the cartridge loading system, showingthe cartridge loaded position P3.

FIG. 47 is a left side view of the cartridge loading system, showing themagnetic head application position P4.

FIG. 48 is a right side view of the cartridge loading system, showingthe magnetic head application position P4.

FIG. 49 is a left side view of the cartridge loading system, showing thefail-safe return position P5.

FIG. 50 is a right side view of the cartridge loading system, showingthe fail-safe return position P5.

FIG. 51 is a front cross-sectional view of the cartridge loading system,showing the cartridge holder at cartridge insertion and drawn-inpositions P1 and P2.

FIG. 52 is a front cross-sectional view of the cartridge loading system,showing the cartridge holder at the cartridge loaded and magnetic headapplication positions P3 and P4.

FIG. 53 is a front cross-sectional view of the cartridge loading system,showing the magnetic head base at cartridge insertion and drawn-inpositions P1 and P2.

FIG. 54 is a front cross-sectional view of the cartridge loading system,showing the cartridge holder at the cartridge loaded position P3.

FIG. 55 is a front cross-sectional view of the cartridge loading system,showing the cartridge holder at the magnetic head application positionP4.

FIG. 56 is a plan view of an embodiment of an encoder cam gear accordingto the invention.

FIG. 57 is a cartridge loading timing diagram according to theinvention.

FIG. 58 is a magnetic head application timing diagram according to theinvention.

FIG. 59 is a magnetic head removal timing diagram according to theinvention.

FIG. 60 is a cartridge unloading timing diagram.

FIG. 61 is a timing diagram showing actuation of an electromagneticfail-safe mechanism according to the invention.

FIG. 62 is a drive mechanism return timing diagram according to theinvention, following the actuation of FIG. 61.

FIG. 63 is a magnetic head re-application timing diagram according tothe invention, following the return of FIG. 62.

FIG. 64(a) shows an embodiment of a timing control system according tothe invention in the cartridge insertion position P1.

FIG. 64(b) shows the embodiment of a timing control system in thecartridge drawn-in position P2.

FIG. 64(c) shows the embodiment of a timing control system in thecartridge loaded position P3.

FIG. 64(d) shows the embodiment of a timing control system in themagnetic head application position P4.

FIG. 64(e) shows the embodiment of a timing control system in themagnetic head application position P4a, following the "cocking" of theelectromagnetic fail-safe mechanism.

FIG. 65 shows the embodiment of a timing control system in the fail-safereturn position P5.

FIG. 66 is a left side perspective view of an embodiment of a shutteroperating mechanism according to the invention.

FIG. 67 is a right side perspective view of the embodiment of a shutteroperating mechanism.

FIG. 68 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 69 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 70 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 71 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 72 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 73 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 74 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 75 is a side schematic view of the embodiment of a shutteroperating mechanism.

FIG. 76 is a front cross-sectional view of an embodiment of a verticalpositioning system according to the invention.

FIG. 77 is a bottom plan view of an embodiment of a horizontalpositioning system according to the invention.

FIGS. 78(a) and 78(b) are detailed views of the embodiment of ahorizontal positioning mechanism, showing dynamic positions.

FIG. 79 is a cross-sectional side view of the embodiment of a horizontalpositioning mechanism.

FIG. 80 is a side schematic view of an embodiment of a magnetic headcarriage locking mechanism according to the invention, showing a firstposition.

FIG. 81 is a side schematic view of the embodiment of a magnetic headcarriage locking mechanism, showing a second position.

FIG. 82 is a detailed plan view of the embodiment of a magnetic headcarriage locking mechanism.

FIG. 83 is a detailed side view of the embodiment of a magnetic headcarriage locking mechanism.

FIG. 84 is a flow chart describing an embodiment of a headsynchronization control process according to the invention, showing amain routine.

FIG. 85 is a flow chart describing the embodiment of a headsynchronization control process, showing a first part of a magnetic headapplication and head synchronization routine.

FIG. 86 is a flow chart describing the embodiment of a headsynchronization control process, showing a second part a magnetic headapplication and head synchronization routine.

FIG. 87 is a flow chart describing the embodiment of a headsynchronization control process, shoeing a magnetic head removalroutine.

FIG. 88 is a side schematic of the MO disk drive, describing theembodiment of a head synchronization control process.

FIG. 89 is a side schematic of the MO disk drive, describing theembodiment of a head synchronization control process.

FIG. 90 is a side schematic of the MO disk drive, describing theembodiment of a head synchronization control process.

FIG. 91 is a side schematic of the MO disk drive, describing theembodiment of a head synchronization control process.

FIG. 92 shows an optical housing, including a beam splitter arrangement.

FIG. 93 is a detailed view of the beam splitter arrangement.

DESCRIPTION OF THE EMBODIMENTS

The subsystems and other portions of the MO disk drive are describedfollowing a description of the general structure and components of an MOdisk drive 10 according to the invention. In order of description, thesubsystems and other portions are:

(a) a first mounting structure 20 to attach a front panel 22 to a mainframe 18 of an MO disk drive 10;

(b) a second mounting structure 20 to attach a front panel 22 to a mainchassis 18 of an MO disk drive 10;

(c) an embodiment of a automatic cartridge loading system 52 to move adisk cartridge 42 from an insertion position to an operating position inan MO disk drive 10, according to the invention;

(d) an embodiment of a timing control system 60 to control the cartridgeloading system 52 of an MO disk drive 10 according to the invention;

(e) a first embodiment of an shutter operating mechanism 40 for acartridge slot shutter 38 of an MO disk drive 10 according to theinvention;

(f) an embodiment of a magnetic head vertical positioning system 64 ofan MO disk drive 10 according to the invention;

(g) an embodiment of a magnetic head horizontal positioning system 66 ofan MO disk drive 10 according to the invention;

(h) an embodiment of a magnetic head carriage lock mechanism 70 of an MOdisk drive 10 according to the invention;

(i) an embodiment of a control system for synchronizing the movements ofa magnetic head 14 and an optical head 16 of an MO disk drive 10according to the invention; and

(j) a beam splitter arrangement 74 for an MO disk drive 10.

GENERAL DESCRIPTION

FIGS. 1 to 20 show the basic structure of a magneto-optical disk drive10 to which the embodiments of the present invention are applied. Thedisk drive 10 is shown in front, side, rear, and plan views in FIGS. 1,2, 3, and 4 respectively. An exploded view of the disk drive 10 appearsin FIGS. 7(a) and 7(b). The left and right sides of the MO disk drive10, and of its component parts, are hereinafter defined as the left andright sides as seen from the viewpoint of FIG. 1. The MO drive accepts aconventional magneto-optical disk cartridge 42 (disk cartridge 42),shown in FIGS. 5 and 6.

As shown in FIG. 5, the disk cartridge 42 houses a freely rotatableconventional magneto-optical disk 12, the disk 12 comprising a platter12a and hub 12b. The disk 12 may be read-only (both surfaces readable)or read-write (only one surface readable/writable). The disk cartridge42 comprises access openings 42a, 42a on top and bottom sides, whichexpose the hub 12b and a substantially rectangular area of the platter12a. The openings 42a are covered by a cartridge shutter 46, which isslidable by means of a detent notch 46a to expose the access openings42a on both sides of the cartridge 42, as shown in FIG. 6. Loadingnotches 42e are formed on both lateral sides of the cartridge 42 at therear end, and notch entry slopes 42c lead into the loading notches 42e.

The disk platter 12a carries identification information, including thetype of disk (single or double sided) and data transfer standardinformation. Information regarding the type of disk carried isconventionally written in MFZ (Manufacturer's Formatting Zone) controltracks at the periphery of the disk platter 12a. Data transfer standardinformation, which identifies the disk 12 as a 4000 rpm ISO(International Standards Organization) standard disk or a 3000 rpm ECMA(European Computer Manufacturers Association) standard disk is encodedon the innermost region of the platter 12a on a PEP (Phase Encoded Part)control track.

The housing of the MO disk drive 10 according to the invention, shown inFIG. 2, comprises a main frame 18, a mounting base 24, a loading chassis26, and a top cover 28. The housing further comprises a rear cover 30,which serves as an upper rear housing portion, and a control chambercover 32, which serves as a lower rear housing portion.

The main frame 18 comprises left and right L-shaped side panels, eachside panel having a base portion 18a and a vertical portion 18b, and thetwo side panels connected to each other by a connecting plate 90 (shownin FIG. 22). The front panel 22 includes a slot 34 through which a diskcartridge 42 may be inserted, and the front panel 22 is attached to theleft and right vertical portions 18b by means of a mounting structure 20(described later). The mounting base 24 is supported by and fixed to thetop edges of the base portions 18a on both sides.

The loading chassis 26 is attached above the mounting base 24, and thetop cover 28 covers the top of the loading chassis 26. A cartridgeinsertion slot 36 in the front of the loading chassis corresponds to theslot 34 in the front panel. A movable shutter 38 (described later)covers the slots 34 and 36 when closed. The rear cover 30 serves tocover a rear opening between the mounting base 24 and the loadingchassis 26. Finally, the housing is fully closed by the control chambercover 32 (see FIG. 3), which covers a lower rear opening between thebase portions 18a of the main frame 18. The control chamber isventilated by perforations 32a in the control chamber cover 32, andclosed at the bottom by a plate (not shown). Control circuit boards 124aand 124b (shown in FIGS. 10 and 11) comprising control circuits forlinear motors for a magnetic head 14 and an optical head 16 are stackedin the control chamber under the mounting base 24.

The mounting base 24, top cover 28, rear cover 30, and shutter 38 definea loading space that is protected from dust, dirt and debris except whenthe cartridge 42 is being inserted or ejected. The cartridge shutter 46is closed during injection or insertion, and protects the disk 12 whenthe cartridge 42 during these operations. Thus, the disk 12 is alwaysprotected from dirt and dust.

A gear chassis 118 is fixed to the top of the loading chassis 26 towardsthe front end of the drive 10, in the position shown in FIG. 10. Thegear chassis 118 is supported by the loading chassis 26 at fasteningtabs 26g and 188 (the fastenings shown in FIG. 20). The gear chassis 118supports a motor 56, which ultimately drives the cartridge loadingsystem 52 through a reduction gear train 236. The gears of the geartrain 236 are rotatably supported by the gear chassis 118. The motor 56is controlled by a servo circuit board 120 that is fixed to the top ofthe gear chassis 118, and is shielded by a heat guard plate 122 attachedto the top cover 28. The circuit board 120 includes a synchronous servocontrol circuit, which drives the motor 56 according to sensor inputs tocontrol vertical movement of both a disk cartridge holder 100 and amagnetic head mounting base 62.

As shown in FIGS. 8 and 9, the mounting base 24 supports an optical headcarriage 128 by means of a linear bearing 126. The optical head 16 issupported on the optical head carriage 128, and is therefore linearlymovable in the radial direction of a loaded disk 12 by means of thebearing 126. The optical head carriage 128 further comprises a carriagearm 148 that extends in the radial direction of a loaded disk 12, awayfrom the center of the loaded disk 12, and a reflector plate 154 ismounted at the remote end of the carriage arm 128.

A pair of yokes 132, adjacent to and parallel to the linear bearing 126,are supported by the mounting base 24 on the left and right sides of theoptical head carriage 128. A pair of coils 130, corresponding to theyokes 132, are attached to the movable optical head carriage 128 andsurround the yokes 132. Together, the coils 130 and yokes 132 constitutea linear motor 134, and the optical head carriage 16 is moved back andforth in the disk 12 radial direction by means of the linear motor 134.

The optical head 16, comprising an objective lens 146 (shown in FIG. 8),converges a laser flux transmitted from a laser unit 72 onto therecording surface of a loaded disk 12. In a reading mode, a relativelyweak laser flux is applied to the disk 12, and a signal detector 376(described later) receives the reflected light. The reflected light isinterpreted by the signal detector 376 by utilizing the well-known Kerreffect. In a writing mode, as the disk 12 rotates, a stronger laser fluxis applied to one side of the disk 12, raising the temperature of arecording substrate above its Curie point, while the magnetic head 14impresses a polarization on the disk 12 from the other side of the disk12, altering the optical properties of the disk 12 at the writing point.

Cartridge Holder 100

The cartridge holder 100 is shown in detail in FIGS. 12 and 13. Theholder 100 is movably supported in the loading chassis 26 as shown inFIGS. 7(a) and 7(b). A cartridge 42 inserted into the MO drive 100through the slots 34 and 36 is held and vertically transported by theholder 100. The cartridge holder 100 comprises a holder top plate 100a,and left and right holder side panels 100b and 100c (left and right asseen from direction X in FIG. 13). The left and right side panels 100band 100c are both bent at the bottom and extend below the cartridgeholder to support the bottom of the cartridge 42 when it is inserted andas it is transported. The top plate 42 comprises an access hole 100a toallow the magnetic head base 62 access to the top of the cartridge.

Front stays 108a and 108b are provided to the left and right sidesrespectively of the front of the top panel 100a of the holder 100. Rearstays 115a and 115b are similarly provided to the two sides of the rearof the top panel 100a. The stays 108a, 108b, 115a, and 115b areproximate to the left and right edges of the cartridge holder 100, andsupport outwardly extending cam follower pins 106a, 106b, 107a, and 107brespectively.

A cartridge shutter opening mechanism 48 is provided to the rear of theholder 100. The mechanism comprises left and right opening arms 50a and50b, each swingably mounted at a rotating axis 110 below the holder toppanel 100a, the axes 110 supported by the holder top panel 100a, and theaxes 110 positioned near the side edges of the rear portion of thecartridge holder 100. The arms 50a and 50b swing in a horizontal plane.Both arms 50a and 50b have a guiding protrusion which fits into arcuategrooves 112 formed in the upper plate 100a; the arcuate grooves 112 arecentered on the rotating axes 110 of arms 50a and 50b, and the swingingmovement of each arm 50a, 50b is guided and limited by the correspondingarcuate groove 112. Torsion springs 114, mounted on axes 110, provided atorsion bias to arms 50a, 50b, biasing the arms 50a, 50b towards thefront of the holder 100. Right arm 50b is mounted to swing below leftarm 50a, such that the arms 50a and 50b do not interfere with eachother. Each arm 50a, 50b has a engaging knob at its distal end. When acartridge 42 is inserted, one of the arms 50a or 50b (depending onwhether the top or the bottom side of a loaded cartridge is loaded)always engages the detent notch 46a on the cartridge shutter 46 of aloaded cartridge 42. As the cartridge 42 is pushed into the holder 100,the arms 50a and 50b swing as they are pushed back (as shown in FIGS. 36and 37), and the swinging action of the engaged arm 50a or 50b opens thecartridge shutter 42 by means of the detent notch 46a engagement withthe arm 50a or 50b.

Magnetic Head Base 62

The magnetic head base 62 is shown in a perspective view in FIG. 14. Themagnetic head 14 is supported by a tapering cantilevered plate spring172, fixed at one end to the magnetic head carriage 68 by a fixing screw174. The plate spring 172 biases the magnetic head 14 towards the disk12, but is stopped by a stopper plate 176. The magnetic head 14 is ofthe "flying head" type, resiliently held by the plate spring 172 toallow the head 12 to be supported by a film of air generated by aspinning disk 12.

The magnetic head carriage 68 is supported on the underside of amagnetic head base 62 by means of a linear bearing 156. The magnetichead carriage 68 is freely movable in the radial direction of a loadeddisk 12 by means of the bearing 156. A pair of yokes 160, adjacent andparallel to the linear bearing 156, are supported by the magnetic headbase 62 on the left and right sides of the magnetic head carriage 68. Apair of coils 158, corresponding to the yokes 160, are attached to themovable magnetic head carriage 68 and surround the yokes 160. Together,the coils 158 and yokes 160 constitute a linear motor 162 (shown in FIG.14 and in cross-section in FIG. 9), and the magnetic head carriage 68 ismoved back and forth in the radial direction of the disk 12 by means ofthe linear motor 162. The magnetic head carriage 68 further comprises acarriage arm 170 that extends in the radial direction of a loaded disk12, away from the center of the loaded disk 12, and a pair ofphotocouplers 150 and 152 that are mounted in order along the length ofthe carriage arm 170, at the bottom of the rear end of the carriage arm170. An L-shaped stopper hook 354 (see FIGS. 80 and 81) is provided tothe tip of the rear end of the carriage arm 170, and the stopper hook354 functions in association with the magnetic head carriage lockingmechanism 70.

Each of the photocouplers 150 and 152 comprises a light emitting deviceand a light receiving device. The photocouplers emit light towards andreceive light from the reflector plate 154 mounted on the optical headcarriage 128. The output signals from the light receiving devices of thephotocouplers are used as synchronous movement detecting signals. Theoptical head 16 and the magnetic head 14 are arranged such that when thetwo heads 16, 14 become aligned, the reflector plate 154 is midwaybetween the photocouplers 150 and 152. Thus, the tracking alignment ofthe two heads 16, 14 with each other in the radial direction of the disk12 is achieved by actively adjusting the positional relationship betweenthe two head carriages 68, 128 until each photocoupler 150, 152 detectsthe same amount of reflected light. The photocouplers 150, 152 andreflector plate 154 function in association with the control system forsynchronizing the heads 14, 16.

The magnetic head base 62 is bent downwards at right angles at bothright and left sides, and positioning recesses 62a are formed on eachbend at the front of the magnetic head base 62. The positioning recesses62a function in association with the vertical positioning system 64.Front cam pins 178a, 178b project outwardly from the left and rightfront sides of the magnetic head base 62, and rear cam pins 179a, 179bproject outwardly from the left and right rear sides of the base 62. Thecam pins 178a, 178b, 179a and 179b function in association with theautomatic cartridge loading system 52. Tapered position determining pins334a and 334b are provided towards the left and right sides respectivelyof the rear of the magnetic head base 62. The position determining pins334a and 334b function in association with the horizontal positioningsystem 66.

Cam Plates 102 and 104

The control cam plates 102 and 104 are shown in detail in FIGS. 15 to19. The control cam plates 102 and 104 are each unitarily molded from aplastic. FIG. 15 shows the internal (towards the inside of the drive)side of the left control cam plate 102, and FIG. 16 shows the externalside of the left control cam plate 102. The left control cam plate 102comprises, in order from direction X in FIG. 16, a shutter blademovement cam groove 101a, a cartridge holder movement front cam groove103a, a magnetic head base movement front cam groove 109a, a cartridgeholder movement rear cam groove 105a, a cam plate guide groove 192, amagnetic head movement rear cam groove 111a, and a pre-load cam groove113.

FIG. 17 shows the internal side of the right control cam plate 104, andFIG. 18 shows the external side of the right control cam plate 104. Theright control cam plate 104 comprises, in order from direction X in FIG.17, a shutter blade movement cam groove 101b, a cartridge holdermovement front cam groove 103b, a magnetic head base movement front camgroove 109b, a cartridge holder movement rear cam groove 105b, a camplate guide groove 194, and a magnetic head base movement rear camgroove 111b.

The cam plate guide grooves 192 and 194, on control cam plates 102 and104 respectively, extend in the loading direction X. Notches 102a and104a, formed in the frontal portion of the respective control cam plates102 and 104, serve as engaging points for the control cam plates 102 and104 to be moved back and forth by the automatic cartridge loadingmechanism 52.

The magnetic head base cam grooves 109a, 109b, 111a, and 111b furthercomprise resilient pressure members 200a, 200b, 201a, and 201brespectively, as shown in FIGS. 15 through 18. The resilient pressuremembers 200a, 200b, 201a, and 201b are unitarily formed and cantileveredfrom the plastic bodies of control cam plates 102 and 104, and areparallel to the lowest positions of their respective cam grooves. Asshown in FIGS. 15 and 16, the resilient pressure members 200a and 201aare biased downward by a wire spring 202, and the resilient pressuremembers 200b and 201b are biased downward by a wire spring 204. Theresilient pressure members function in association with the verticalpositioning system 64.

The lower half of each of the magnetic head base cam grooves 109a, 111aand 109b, 111b penetrate through the respective cam plate 102 and 104,as shown in FIGS. 16 and 18. The remaining cam grooves open only towardsthe inside of the cam plates 102 or 104.

Cam groove profiles, formed in cam plates 102 and 104, and defining themovements of various parts of the drive 10, are shown in FIG. 19.Cartridge holder movement cam grooves 103a, 103b, 105a, and 105b, sharea cam groove profile A defining the vertical movements of the cartridgeholder 100. Magnetic head base movement cam grooves 109a, 109b, 111a,and 111b share a cam groove profile B defining the vertical movements ofthe magnetic head base 62.

The cam profile A, defining the vertical movement of the cartridgeholder 100, has two horizontal surfaces, A1 and A3, each of whichdefines a vertical level or position of the cartridge holder 100. Thesurface A1 defines a cartridge insertion position A1 (vertical level).At the cartridge insertion position A1, a cartridge 42 may be inserted,and will be drawn into the cartridge holder 100. The cartridge insertionposition A1 of the cartridge holder 10 is also the position in which acartridge 42 is ejected and may be removed from the drive 10. Thesurface A3 defines a cartridge loaded position A3 (vertical level). Atthe cartridge loaded position A3, a cartridge 42 has been moved to aposition to be ready for reading or writing. Between A1 and A3, aninclined surface A2 defines a guided movement and a rate of movementfrom cartridge insertion position A1 to cartridge loaded position A3.

The cam profile B, defining the vertical movement of the magnetic headbase 62, has three horizontal surfaces, B1, B3, and B5, each of whichdefines a position (vertical level) of the magnetic head base 62. Thesurface B1 defines an "idle" position B1. At the idle position B1 of themagnetic head base 62, the magnetic head base 62 is held at its highestposition so that the cartridge holder 100 may be kept in the cartridgeinsertion position to accept or eject a cartridge 42. The idle positionB1 of the magnetic base 62 is largely simultaneous with the cartridgeinsertion position A1 of the cartridge holder 10 along their respectivecam profiles B and A. At the magnetic head base "standby" position B3,the magnetic head base is at a position ready to move into writingposition, yet safely away from a loaded disk 12. The surface B5 definesa magnetic head base writing position B5. At the magnetic head basewriting position B5, a loaded disk 12 is spinning and the magnetic head14 is flying on an air cushion, ready for writing. Between B1 and B3, aninclined surface B2 defines a guided movement and a rate of movementfrom magnetic head base idle position B1 to magnetic head base standbyposition B3. Between B3 and B5 an inclined surface B4 defines a guidedmovement and a rate of movement from magnetic head base standby positionB3 to magnetic head base writing position B5.

The cam profile C, defining the opening and closing movements of theshutter blade 38, has three horizontal surfaces, C1, C3, and C5, each ofwhich defines a position (from open to closed) of a mechanism 40controlling the shutter blade 38. Surface C1 and C3 both define a closedpositions C1, C3 of the shutter blade 38, and surface C2 corresponds toa fully open position of the shutter blade 38. Surfaces C2 and C4 definea guided movement and rate of movement of the shutter operatingmechanism 40, between closed position C1 and open position C3 andbetween open position C3 and closed position C5.

Loading Chassis 26

The loading chassis is shown in perspective detail in FIG. 20. Theloading chassis 26 is unitarily formed, including a front portion 26c,and a pair of side portions 26a and 26b extending back in the loadingdirection from left and right sides respectively of the front portion26c. A plurality of supports 190 for attaching the loading chassis 26 tothe mounting base 24 are bent in from the lower inside front regions ofthe side portions 26a and 26b. Recessed plate guide channels 27a and 27bextend along the length of the left and right sides respectively, andare formed towards the upper part of each side by bending a U-channeltowards the interior of the drive 10. A plurality of supports 188 forattaching the gear chassis 118 are bent in from the inside upper frontregion of the channels 27a and 27b. A control cam plate is provided toeach plate guide groove; cam plate 102 is slidable in the left guidegroove 27a, and cam plate 104 is slidable in the right guide groove 27b.Guide pins 196 and 198, provided to the plate guide channels 27a and27b, fit into the corresponding cam plate guide grooves 192 and 194 asshown in FIG. 34, thus ensuring that the movement of the cam plates 102and 104 is restricted to movement back and forth in the direction X.

Magnetic head base guide slots 180a, 180b, 181a, and 181b are formedthrough the plate guide channels 27a and 27b on both sides and at frontand back, corresponding to the cam pins 178a, 178b, 179a, and 179b ofthe magnetic head base 62. The guide slots 180a, 180b, 181a, and 181aare vertical through slots, and when the cam pins 178a, 178b, 179a, and179b are inserted in the corresponding guide slot, the magnetic headbase 62 is constrained to move only vertically within the drive 10.

The cam follower pins 178a, 178b, and 179a, 179b of the magnetic headbase 62 penetrate into the plate guide channels 27a and 27b, via themagnetic head base guide slots 180a, 180b, and 181a, 181b, to mate withcam grooves 109a, 109b, and 111a, 111b in the left and right control camplates 102 and 104 respectively. Cam follower pin 178a penetrates intoplate guide channel 27a through slot 180a to mate with cam groove 109a;pin 178b penetrates into channel 27b via slot 180b to mate with 109b;179a penetrates into 27a through 181a to mate with 111a; and 179bpenetrates into 27b through 181b to mate with 111b. The guide slots180a, 180b, and 181a, 181b serve to guide the magnetic head base 62 tomove vertically in response to sliding movements of the control camplates 102 and 104 in the plate guide grooves 27a and 27b.

The movements of the cartridge holder 100 are also controlled by thecontrol cam plates 102 and 104. The cartridge holder cam follower pins106a, 106b, 107a, and 107b are constrained by cartridge holder guideslots 182a, 182b, 183a, and 183b, respectively, to move only vertically.The cam follower pins 106a, 106b, 107a, and 107b penetrate into theplate guiding channels 27a and 27b via the guide slots, where they matewith respective cartridge holder cam grooves 103a, 103b, 105a, and 105b.The guide slots 182a, 182b, 183a, and 183b serve to guide the cartridgeholder 100 to move vertically in response to sliding movements of thecontrol cam plates 102 and 104 in the plate guide grooves 27a and 27b.

The guide slots and plate guide grooves function in association with theautomatic cartridge loading system 52. The cartridge holder 100 andmagnetic head base 62 are shown in various positions in side and frontviews in FIGS. 41 through 55. The loading chassis 26 further comprisesreference surface tabs 26f and 26g for precisely positioning themagnetic head base 62, which function in association with the verticalpositioning system 64.

(a) and (b) Front Panel Mounting Structures 20 and 20'

A front panel mounting structure 20 is shown in FIGS. 21 through 24, andcomprises mating parts on the front panel 22 and main frame 18. Thefront panel mounting structures 20 and 20' use mounting hooks 76 on theinside face of the front panel 22 to securely fasten the front panel 22to the main frame 18 without any visible fastenings on the front panel22.

As shown in FIG. 21, mounting hooks 76 are provided at the top of theback of the front panel 22 on both of the left and right sides. Themounting hooks 76 are L-shaped plates, fixed at a tip of a support legof the hook 76, and the remaining leg projecting upwards and having aheight H1 as shown in FIG. 23. The left and right mounting hooks 76 eachmate to a hooked groove 84 provided to each of the left and rightvertical portions 18b of the main frame side panels. Entrances to thehooked grooves 84 are made to be slightly larger (height H2) than theheight of the upwardly projecting leg 76a of the mounting hooks 76, andeach hooked groove 84 has a vertical recess 84a.

A mounting tab 78 having a U-slot 82 is formed on each of the left andright bottom sides of the back of the front panel 22. The mounting tabs78 mate to frame tabs 86 of the main frame 18, each frame tab 86 havinga screw hole 88. The frame tabs 86 are recessed towards the main frameinterior by an amount corresponding to the thickness of the mountingtabs 78, allowing the mounting tabs 78 to slide outside the frame tabs86 when the front panel 22 is attached. The U-slots 82 of the mountingtabs 78 are fixed to the frame tab screw holes 88 by screws 80.

The front panel 22 is attached to the main frame 18 by inserting themounting hooks 76 into the hooked grooves 82, as shown in FIG. 24. Thefront panel is then slid up so that the upwardly projecting legs 76a ofthe mounting hooks 76 fits into the vertical recesses 84a of the hookedgrooves 84. The U-slots 82 of the mounting tabs 78 are then aligned withthe frame tab screw holes 88, and the front panel 22 is fixed inposition with the screws 80.

The front panel mounting structure allows the front panel to be quickly,securely and accurately mounted using only two screws 80, 80, andfurther does not have any panel mounting fixtures visible from the frontof the drive 10.

FIGS. 25 to 27 show a second mounting structure 20' for a front panel 22of an MO drive 10. The second structure is different in that pins 96 areprovided to the mounting tabs 78, and the pins snap into correspondingholes 98 provided to the left and right vertical side panels 18b of themain frame 18. There are no frame tabs as in the first embodiment, andthe side panels are not recessed in the region where the pins 96 andholes 98 mate; instead, the holes 98 are provided in the undeformed sidepanels 18b. As shown in FIG. 26, the mounting tabs 78 are designed toflex inwardly to allow the front panel 22 to be pressed into position.

The attachment procedure for the second front panel mounting structure20' is similar to the procedure for the first structure. However, in thesecond structure, after the upwardly projecting legs 76a are properlypositioned mounting hooks are properly positioned in the verticalrecesses 84a, the front panel 22 is pressed forward, the mounting tabs78 flex inwardly as shown in FIG. 26, and the pins 96 snap into place inthe holes 98 as shown in FIG. 27.

The front panel mounting structure allows the front panel to be quickly,securely and accurately mounted using no screws and further does nothave any panel mounting fixtures visible from the front of the drive 10.

(c) Cartridge Loading System 52

An embodiment of a cartridge loading system 52 according to the presentinvention appears in FIGS. 28 through 55. The cartridge loading system52, controlled by the timing control system 60, automatically draws thecartridge 42 into the cartridge holder 100, and moves the cartridgeholder 100 and cartridge 42 into the cartridge loaded position.

FIGS. 28 through 31 show plan views of a driving mechanism 116, withvarious components removed to show different levels of functionalcomponents as the views proceed downward in level from FIG. 28 to FIG.31. As shown in FIG. 28, the cartridge loading system 52 comprises apair of control cam plates 102 and 104, a cartridge draw-in mechanism232 (shown in FIGS. 13 and 35), a driving mechanism 116. The cartridgeloading system functions in association with an electromagneticfail-safe mechanism 288, visible in FIGS. 28 through 30. The drivingmechanism 116 engages with and drives both the cartridge draw-inmechanism 232 and the control cam plates 102 and 104.

Driving Mechanism 116

The driving mechanism 116 is shown in plan views in FIGS. 28 through 31and in side views in FIGS. 32 and 33. The driving mechanism 116comprises a driving motor 56 mounted to the bottom plate of the gearchassis 118, an encoder cam gear 234, and a reduction gear train 236.The reduction gear train 236 transfers the motive power of the motor 56to the encoder cam gear 234. The encoder cam gear 234 also functions inassociation with the timing control mechanism 60. The driving mechanism116 drives both the cartridge draw-in mechanism and a control cam platedriving mechanism. The control cam plate driving mechanism drives thecontrol cam plates 102 and 104 from the encoder cam gear 234, theencoder cam gear driven from the motor 56 by the gear train 236.

The driving motor 56 is mounted towards the front central area of thebottom plate of the gear chassis 118, with the drive axis orientedhorizontally and transverse to the cartridge loading direction, in thedirection Y as shown in FIG. 31. A worm gear 56a is fixed to the driveaxis of the motor 56. Three reduction gears 238, 240 and 242 arerotatably mounted in a gear train 236, and engaged to the worm gear 56aand the encoder cam gear 234.

Control Cam Plate Driving Mechanism

The encoder cam gear 234 is coupled to a sector gear 310a of a gearlever 310 (shown in FIGS. 28 and 29), through a driving pinion 234aformed on the encoder cam gear 234. The gear lever 310 is rotatablymounted at its approximate center at an axis 282, the axis 282approximately equidistant from the control cam plates 102 and 104. Anaxis pin 314 is mounted at the end of the gear lever 310 opposite thesector gear 310, and the axis pin 314 projects upward. A swingable catcharm 312 is rotatably mounted on the axis pin 314. The catch arm 312 isbiased in a clockwise (as seen in FIG. 28, from a viewpoint lookingdownwards from the top of the drive 10) direction by a torsion spring316 mounted on the axis pin 314. The catch arm 312 is substantiallyL-shaped, with the axis pin 314 at the elbow of the L shape. The shorterarm of the L shape comprises an upright projection 312c. The projection312c is positioned to contact a cocking axis pin 302 (shown in FIGS. 28through 31) at a frontal position of the swinging range of the gear arm310. The longer arm of the L shape of the catch arm 312 comprises a hookcatch 312a at the distal end of the longer arm, and a concave catch 312bapproximately halfway along the longer arm. As the L-shaped catch arm312 is biased in a clockwise direction by the torsion spring 316, theconcave catch 312b is thereby urged to engage a driving pin 298 attachedto a link arm 284.

The link arm 284 (shown in FIG. 31) is rotatably mounted to the axis pin282, axis pin 282 being the same axis pin to which the gear lever 310 isrotatably mounted. However, the link arm 284 is mounted to the axis pin282 on the bottom of the gear chassis bottom plate 118d, whereas thegear lever 310 is mounted to the axis pin 282 on the top of the gearchassis bottom plate 118c. The link arm 284 extends across the gearchassis 118 from the control cam plate 102 to the control cam plate 104,and comprises engaging pins 292a and 292b at the two ends of the linkarm 284. The engaging pins 292a and 292b engage the control cam plates102 and 104 respectively at engaging slots 102a and 104a. The drivingpin 298 projects upwardly from the link arm 284 through the bottom plate118c via a guide groove 294. The guide groove 294 is arcuate, and iscentered about the axis pin 282.

As described, the gear lever 310 is coupled via the sector gear 310a anddriving pinion 234a to the driven encoder cam gear 234 at one end, andhas a clockwise-biased rotatable catch arm 312 at the remaining end. Thecatch arm 312 (specifically, the concave catch 312b) on the gear lever310 can engage the driving pin 298 of the link arm 284, and the link arm284 is engaged to the control cam plates 102 and 104 at both ends of thelink arm 284. Thus, the driving force of the motor 56 is transmitted tothe control cam plates 102 and 104, driving the plates 102 and 104 inopposite directions relative to each other.

Electromagnetic Fail-safe Mechanism 288

If the power supply to the disk apparatus 10 is interrupted for anyreason, a spindle motor 44 which drives the disk 12 stops, and the diskstops rotating. When operating, the "flying" magnetic head 14 is onlyheld away from the disk by air pressure generated by the spinning disk12, and the stopping of the disk 12 therefore creates the risk of a"head crash", or contact of the magnetic head 14 to the disk 12 surface.This contact may result in damage to the disk 12 surface, and to preventdamage to the disk 12, the described embodiment of the inventionincorporates an electromagnetic fail-safe mechanism 288 to return thecartridge holder 100 to a standby position away from the magnetic head14. The electromagnetic fail-safe mechanism 288, visible in FIGS. 28 to30 and FIGS. 36 to 40, comprises a locking arm 300, an armature contact300a, a return arm 304, a return spring 318 and an electromagnet 290.The locking arm 300 is positioned along the outer circumferential edgeof the guide groove 294 of the bottom plate 188d, and is rotatablymounted to the bottom plate 188d at the trigger axis pin 302, thetrigger axis pin 302 proximate to the front end of the guide groove 294.The electromagnet 290 is mounted to the bottom plate 118d at a positionalong the swinging range of the locking arm 300. The locking arm furthercomprises a ferromagnetic armature contact 300a, which is rotatablymounted to the distal end of the locking arm 300, such that the armaturecontact 300a can self-align and abut the electromagnet 290. A portion ofthe inside edge of the locking arm 300 is arcuate, following the samearc as the guide groove 294, and contacts the driving pin 298 for aportion of the swinging travel of the driving pin 298. The locking arm300 is biased to rotate in a counterclockwise direction by a torsionspring 308 provided to the cocking axis pin 302, and the locking arm 300further comprises a recessed concave stopper 300b proximate to the axispin 302. When the driving pin moves forward along the guide groove 294,the driving pin 298 approaches the front end of the guide groove 294 andapproaches the recessed concave stopper 300b. At this point, the lockarm 300 can swing in a counterclockwise direction, and the concavestopper 300b can engage the driving pin 298, at which time the armaturecontact 300a swings to abut the electromagnet 290.

The fail-safe mechanism 288 further comprises the return arm 304. Thereturn arm 304 shares the axis pin 282 with the gear lever 310 and thelink arm 284. The return arm 304 is rotatably mounted to the axis pin282 on top of the bottom plate 188d, but below the gear lever 310. Areturn tension spring 318 is stretched between an end of the return arm304 and a tab on the bottom plate 118d, so that the return arm 304 isbiased to rotate in a counterclockwise direction. A guide pin 320 ismounted on the bottom face of the return arm 304, and the guide pin 320projects downwardly through the bottom plate 118d via a return arm guidegroove 296 in the bottom plate 118d. The guide pin 320 is positioned onthe return arm 304 so that the link arm 284 contacts and pushes theguide pin 320 when the link arm 284 has completed approximately one halfof its range of travel as the link arm 284 swings. When the link arm 284continues in a clockwise swinging direction after completing half itsrange of travel, the return arm 394 swings clockwise in unison with thelink arm 284 by virtue of the contact between the contact pin 320 andthe link arm 284, against the bias of the return tension spring 318.Thus, for approximately the second half of the traveling range of thelink arm 284 in the loading direction (clockwise swinging), the link arm284 is biased to return to the middle point of its traveling range bythe return tension spring 318.

The catch arm 312 is arranged to release the driving pin 298 when thedriving pin 298 is moved to the front end of the guide groove 294 andthe upright projection 312c abuts the cocking axis pin 302. Just beforethe driving pin 298 reaches the point along the groove 294 where thecatch arm 312 releases the driving pin 298, the ferromagnetic contactarmature 300 of the locking arm 300, biased to rotate counterclockwiseby the torsion spring 308, contacts the energized electromagnet 290. Thecontact armature 300, and thereby the locking arm 300, is magneticallyheld, and the concave stopper 300b accepts the driving pin 298. Thepoint where the catch arm 312 releases the driving pin 298 to be held bythe concave stopper 300a corresponds to the magnetic head applicationposition P4. At this point and thereafter, the driving pin 298 is heldby the concave stopper 300b of the locking arm 300.

When power is removed from the electromagnet 290 for any reason, theelectromagnet 290 is de-energized, having no power supply, and thedriving pin 284 is released by the locking arm 300. The link arm 284rotates counterclockwise in unison with the return arm 304, both underthe bias of the return spring 318. The link arm 284 and return arm 304rotate counterclockwise until the guide pin 320 attached to the returnarm 304 abuts the rear side of the return arm guide groove 296. When thelink arm 284 becomes stationary, the driving pin 298 of the link arm 284is held and stopped by the hook catch 312a at the distal end of thecatch arm 312. The positions of the locking arm 300, return arm 304,link arm 284, and catch arm 312 in energized and released states of theelectromagnetic fail-safe mechanism may be seen in FIGS. 64(d) and64(e).

Cartridge Draw-in Mechanism 232

A mechanism to automatically draw a disk cartridge 42 into the cartridgeholder 100 is also linked to the encoder cam gear 234. The cartridgedraw-in mechanism 232 is shown in detail in FIGS. 13, 29 and 35. Thecartridge draw-in mechanism 232 comprises an hook lever 274, a slideplate 268, and a draw-in link member 266. The draw-in mechanism 232 isdriven by means of a cam groove 278 formed in the bottom of the encodercam gear 234, the cam groove 278 guiding the draw-in link member by acam follower pin 270 attached to the draw-in link member 266.

As shown in FIGS. 29 and 35, the draw-in link member 266 is rotatablymounted by means of an axis pin 252 to the top of the bottom plate 118dof the gear chassis 118. The draw-in member 266 is T-shaped, mounted bythe axis pin 252 at one side of the top of the T shape. The base of theT shape of the member 266 is movable under the encoder cam gear 234, andthe cam follower pin 276 protrudes up from the base of the T-shape ofthe member 266 and engages the cam groove 278 formed in the bottom faceof the encoder cam gear 234. The cam groove 278 leads the draw-in member266 to rotate in a clockwise direction as the encoder cam gear rotatescounter-clockwise. A forked guide groove 266a is formed on the remainingside of the top of the T shape of the draw-in member 266.

The forked guide groove 266a engages a driving pin 270 attached to theslide plate 268, driving the slide plate 268. The slide plate 268 isshown in FIGS. 13 and 35. The slide plate 268 is mounted to thecartridge holder 100 by means of guide pins (not shown) on the slideplate 268 and straight grooves (not shown) in the cartridge holder 100,such that the slide plate 268 may only move in a straight line, back andforth in the direction X (shown in FIG. 13). The driving pin 270projects upward from the slide plate 268, and is of sufficient lengththat it may always engage the forked guide groove 266a of the draw-inlink member 266 as the cartridge holder 100 moves vertically relative tothe gear chassis 118. An axis pin 272 and a stopper tab 268b (not shown)are further provided to the slide plate 268, and extend downward intothe cartridge holder 100 via two separate through grooves at a rearportion 268a as shown in FIG. 13.

The L-shaped hook lever 274 is rotatably mounted to the slide plate 268by means of the axis pin 272 at the elbow of the L shape. The axis pin272 extends downward into the cartridge holder 100 via a through groove(not shown), and the hook lever 274 is positioned inside the cartridgeholder 100. A first arm 274a of the hook lever 274 is substantiallyparallel on its internal surface with the rear of an inserted cartridge42. The second arm 274b of the hook lever 274 extends in the unloadingdirection (opposite to direction X), and comprises a rounded hookprojecting inwards toward an inserted cartridge 42. The cartridge hooklever 274 is rotatable between (a) a draw-in position, where the firstarm 274a contacts a cartridge 42 and rotates the hook lever 274 so thatthe rounded hook of the second arm 274b engages a loading notch 42e ofthe cartridge 42, and (b) a release position, where the second arm 274disengages from the loading notch 42e. In the draw-in position, therotating hook lever 274 abuts the stopper tab 268b of the slide plate268 when a cartridge 42 is pushed against the first arm 274a, so thatthe rounded hook of the second arm 274b is in a predetermined positionas it engages the loading notch 42e. Furthermore, the tip of the secondarm 274b is tapered so that it self-aligns when a cartridge 42 isinserted into the cartridge holder 100. A through opening 100g is formedin the side of the cartridge holder 100 to allow some play in thisself-alignment. Thus, as the cam groove 278 guides the draw-in linkmember 266 clockwise, the linked slide plate 268 moves the hook lever274 back from the insertion position as shown in FIG. 28, and the hooklever 274 draws the cartridge 42 into the cartridge holder 100 by meansof the loading notch 42e.

The encoder cam gear 234 is coupled with the motor 56 through the geartrain 236, and only turns when the motor 56 turns. Similarly, the slideplate 268 is connected without play to the draw-in link member 266 bymeans of the follower pin 270. However, in order to satisfy theoperational timing of the system 52, the encoder cam gear 234 mustengage the draw-in link member 266 elastically. Thus, the cam grooveformed 278 on the lower face of the encoder cam gear 234 has a clearance(visible in FIG. 56) to allow play in the engagement between thefollower pin 276 of the draw-in link member 266 and the cam groove 278,and a torsion spring 330 (shown in FIG. 28) is provided to the encodercam gear 234 to bias the pin 276 to contact the wall of the cam groove278 and to bias the slide plate 268 forward. The torsion spring 330surrounds a cylindrical boss 234c formed unitarily and concentrically tothe top of the encoder cam gear 234. The torsion spring 330 is fixed tothe encoder cam gear 234 at one end, and the remaining end extends to arecess 234d formed in the encoder cam gear 234 and contacts the followerpin 276 when the cartridge loading system 52 is in the cartridgeinsertion position.

The movement of the cam follower pin 276 and the draw-in link member 266during a cartridge draw-in operation does not affect the stationaryencoder cam gear 234 due to the play in the cam groove 278.

FIGS. 36 through 55 describe the motion of the cartridge loading system52, but are also descriptive of the timing control mechanism 60. Thedynamic motion of the cartridge loading system 52 is therefore describedfollowing a description of the timing control system 60.

Thus, when a disk cartridge 42 is manually inserted and pushed,activating the timing control system 60, the cartridge 42 isautomatically drawn into the cartridge holder 100. The operator is notrequired to insert a disk cartridge 42 all the way into the disk drive10, and the cartridge loading operation is therefore very easy. Thecartridge 42 is unloaded in an analogous reverse operation, and when acartridge 42 is ejected, the operator may easily access the cartridge42. In the loading operation, the disc cartridge 42 is securely held atthe loading notches 42e by the hook lever 274, making the loadingoperation stable. Similarly, the hook lever 274 holds the disk cartridge42 until the cartridge insertion position P1 when ejecting a cartridge42, and the cartridge ejection process is therefore much more stablethan a conventional spring-loaded ejection system.

(d) Timing Control System 60

An embodiment of an timing control system 60 according to the inventionappears in detail in FIGS. 56 through 65. The timing control system 60uses a unitary encoder cam gear 234 and photo-interruptors sensors 326and 328 to control the loading of a cartridge 42 and the application ofthe magnetic head 14 to a disk. FIG. 56 shows the encoder cam gear 234in detail; FIGS. 57 through 63 show timing diagrams describing theembodiment; and FIGS. 64(a) to 64(e) and 65 show timed positions of thetiming control system 60 and associated mechanisms. The timing controlsystem 60 comprises the encoder cam gear 234, loading sensors 326 and328, a draw-in sensor 260, and an interruptor lever 250.

The encoder cam gear 234, shown in FIG. 56, comprises unitarily formedportions including: driving pinion 234a, driven gear 234b, boss 234c,recess 234d, first encoder rib 322, first encoder rib gap 322a, secondencoder rib 324, and cam groove 278. The driven gear 234b is driven bythe motor 56 via the gear train 236, the driving pinion 234a drives thesector gear 310, and the cam groove 278 guides the follower pin 276 ofthe draw-in link member 266 as previously described.

The first and second encoder ribs 322 and 324 project upwards from thetop of the encoder cam gear 234, and are arcuate forms having a commoncenter at the axis pin 256 of the encoder cam gear 234. The firstencoder rib 322 is formed towards the outer circumference of the encodercam gear 234, and the second encoder rib 324 is formed towards the innercircumference of the gear 234. The first encoder rib 322 has a gap 322aat a predetermined position.

The first encoder rib 322 and the second encoder rib 324 of the encodercam gear 234 are detected by respective (photo interruptor) loadingsensors 326 and 328. The photo interruptors of the loading sensors 326and 328, and of the draw-in sensor 260 described herein, each comprise alight-emitting device and a light-receiving device facing each otherwith an intermediate gap, and turn from normally ON to OFF when the gapis interrupted, and ON again when an interruption is removed.

The first and second loading sensors 326 and 328 are directly mounted ona synchro-servo circuit (not shown) on the lower face of thesynchro-servo base board 120, shown in FIG. 33. The positions of theloading sensors 326 and 328 (shown in FIGS. 64(a) to 64(e) and 65) arepredetermined to detect the rotational position of the encoder cam gear234 as the encoder ribs 322 and 324 interrupt the loading sensors 326and 328.

The first encoder rib 322 is arranged to turn OFF the first loadingsensor 326 at the cartridge draw-in position P1, and then to turn OFFthe first loading sensor 326 until the magnetic head 14 is brought tothe magnetic head application position P4. The gap 322a in the firstencoder rib 322 is arranged to briefly turn ON the first loading sensor326, turning OFF an electromagnet 290 according to the timing of theremoval of the magnetic head base 62 from the magnetic head applicationposition P4. The second encoder rib 324 is positioned to turn OFF thesecond loading sensor 328 at the cartridge loaded position P3.

The axis pin 252, which supports the draw-in link member 266, alsorotatably supports the interruptor lever 250 (visible in FIG. 30). Theinterruptor lever 250 is substantially T-shaped, and is rotatablysupported at one side of the top of the T shape. The interruptor lever250 is biased by a torsion spring 258 provided to the axis pin 252 torotate counterclockwise, and resiliently contacts the draw-in linkmember 266 on the rear side of the draw-in link member 266. The base ofthe T shape of the interruptor lever 250 extends below the bottom plate118d of the gear chassis 118, and a follower pin 262 protrudes upwardfrom the base of the T shape of the interruptor lever 250. The followerpin 262 engages a guide groove 254 formed in the bottom plate 118d ofthe gear chassis 118, and the guide groove 254 defines the rotatingrange of the interruptor lever 250. The follower pin 262 can be pushedby the edge of the link arm 284 at the extreme clockwise position of thelink arm 284. On the remaining side of the top of the T shape of theinterruptor lever 250, a flat and curved interruptor member 250aprotrudes upwardly.

The interruptor member 250a is detected by the (photo interruptor)draw-in sensor 260 in order to control the timing of the cartridgedraw-in operation. The photo interruptor 260 is directly mounted on thesynchro-servo circuit on the lower face of the synchro-servo base board120 (FIG. 33), and the photo interruptor 260 is positioned to detect theinsertion of a cartridge 42 when the interruptor member 250a interruptsthe photo interruptor 260.

The timing control system 60 of the disk drive 10 according to theembodiment begins to operate when a cartridge 42 is inserted into thecartridge holder 100, and the hook lever 274, the slide plate 268, thedraw-in link member 266 and the cam follower pin 276 are pushed to apredetermined position along the loading direction X as shown in FIG.36. At this point, the draw-in link member 266 pushes the interruptormember 250 to interrupt the draw-in sensor 260, and the timing andcontrol of the automatic loading system 52 is actuated.

Timing

The timing of the automatic cartridge loading system 52 is controlledaccording to the timing diagrams shown in FIGS. 57 through 63. In FIGS.57 to 63, PS-A, PS-B, and PS-C represent the photo interruptor signalsgenerated by the loading sensors 326 and 328, and the draw-in sensor 260respectively. Thus, PS-A represents the detection status of firstencoder rib 322 and gap 322a, PS-B represents the detection status ofsecond encoder rib 324, and PS-C represents the status of theinterruptor member 250a of the cartridge draw-in mechanism. SOLE shows acontrol signal fed to the electromagnet 290. LDA and LDB representcontrol signals fed to the motor 56; LDA low (L) and LDB high (H) isforward (loading) rotation, LDA high and LDB low is reverse rotation,and LDA high and LDB high is stopping.

Timing Control System & Cartridge Loading System: Dynamic

The following description of the dynamic operation of the timing controlsystem 60 is also representative of the cartridge loading system 52.

FIG. 57 shows the loading operational timing of the disc cartridge 42and cartridge holder 100. In FIG. 57, the control cam plates 102 and 104are moved from the cartridge insertion position P1, to the cartridgeloaded position P3. The loading sensors 326 and 328 and the draw-insensor 260 are in ON states before a cartridge 42 is inserted and pushedinto the cartridge holder 100. As the disk cartridge 42 is manuallyinserted through the chassis opening 36, the leading edge of the diskcartridge 42 pushes back the hook lever 274 and thereby the slide plate268, rotating the interruptor member 250 as the draw-in link member ismoved by the drive pin 270 attached to the slide plate 268, as shown inFIG. 64(a). The draw-in sensor 260 is turned off by the interruptormember 250 as the member 250 rotates. The automatic control system 52thereby detects that the disk cartridge 42 is pushed to a cartridgeinsertion detection position just past the cartridge insertion positionP1.

FIGS. 36, 41, 42, and 51 are plan, left, right and front viewsrespectively of the status of the cartridge loading system 52 and othermechanisms at the cartridge insertion position P1. FIG. 64(a) is adetailed plan view of the timing control system 60 at position P1. Atthis stage, the cartridge holder 100 is positioned to accept acartridge, and the magnetic head base 62 is in the topmost idleposition.

The structural arrangement of the components fixed to the gear chassis118 are shown in plan view in FIG. 64(a), just as the cartridge 42 isdetected by the draw-in sensor 260. The cartridge holder 100 andmagnetic head carriage 62 have not yet moved as the motor 56 is juststarted. At this point, the first loading sensor 326 is interrupted bythe first encoder rib 322 and is turned OFF, but the motor 56 control isnot changed and the motor 56 continues.

As the motor 56 rotates the encoder cam gear 234 through the gear train236, the follower pin 276 projecting from the draw-in link member 266 isengaged with the cam groove 278 on the bottom of the encoder cam gear234, and the draw-in link member 266 is thereby turned in a clockwisedirection. The forked guide groove 266a of the draw-in link member 266pushes on the slide plate 268 at the driving pin 270, and the slideplate 268 moves in the direction X as shown in FIG. 56. The diskcartridge 42 is engaged at the loading notch 42e with the hook lever274, and the cartridge 42 is drawn into the cartridge holder 100.

Simultaneously, the encoder cam gear 310 drives the sector gear 310aattached to the gear arm 310. Thus, the gear arm 310, including thecatch arm 312, swings in a clockwise direction. The concave catch 312bof the catch arm 312 holds the driving pin 298 of the link arm 284, andthe link arm 284 therefore moves with the gear arm 310. The link arm284, swinging in a clockwise direction, moves the control cam plates 102and 104 in opposite directions, the control cam plate 102 moving towardsthe rear of the disk drive 10 and the control cam plate 104 movingtowards the front of the disk drive 10. The control cam plates continuefrom the cartridge insertion position P1 to the cartridge drawn-inposition P2.

FIGS. 37, 43, 44 are plan, left, and right views respectively of thestatus of the cartridge loading system 52 and other mechanisms at thecartridge drawn-in position P2. The front view of position P2 appearsthe same as the cartridge insertion position P1 as the cartridge holder100 and magnetic head base 62 have not started to descend, and is shownin FIG. 51. FIG. 64(b) is a detailed plan view of the timing controlsystem 60 at position P2. After the disk cartridge 42 is entirely drawninto the cartridge holder 100 at position P2, the motor 56 and encodercam gear 234 continue to rotate. The disk draw-in operation is complete,and the driving pin 276 stops rotating the draw-in link lever as itpasses into a portion of the cam groove 278 which maintains the pin 276in a constant position.

The gear arm 310 and link arm 284 continue to turn clockwise driven bythe encoder cam gear 234, the link arm 284 driving the control camplates 102 and 104. As shown in FIG. 19, the control cam profiles guidethe cartridge holder 100 to descend at this stage, guiding the cam pins106a, 106b, 107a, and 107b on the inclined portions A2 (corresponding toportions of cam grooves 103a, 103b, 105a, and 105b on the control camplates 102 and 104). Similarly, the magnetic head base 62 descends asthe cam pins 178a, 178b, 179a, and 179b are guided by the inclinedportion B2 (corresponding to portions of cam grooves 109a, 109b, 111a,and 111b on the control cam plates 104 and 104).

The driving motor 56 stops when the second loading sensor 328 isinterrupted by the second encoder rib 324 and is turned OFF. At thispoint, the cartridge holder 100 has descended to the cartridge loadedposition P3.

FIGS. 38, 45, 46, and 52 are plan, left, right and front viewsrespectively of the status of the cartridge loading system 52 and othermechanisms at the loaded position P3. FIG. 64(c) is a detailed plan viewof the timing control system 60 at position P3. The cartridge loadedposition P3 is just before the magnetic head "standby" position, and thetwo positions may be considered functionally equivalent. At thecartridge loaded position P3, the spindle motor 44 begins to rotate thedisk 12, and the optical head 16 reads the PEP control track informationcoded on the inner tracks.

FIG. 58 shows a timing chart for the cartridge loading operation fromthe cartridge loaded position P3 to the magnetic head applicationposition P4 of the magnetic head base 61. The magnetic head 14 isapplied when a writing operation is to be carried out. If the controlcircuit (not shown) transmits an instruction to apply the magnetic head14, the electromagnet 290 is energized to attract the ferromagneticarmature contact 300a of the locking arm 300. At the same time, thedriving motor 56 is restarted in the forward (loading) direction, andthe gear arm 310 and link arm 284 proceed further in a clockwisedirection, moving the control cam plates 102 and 104 further in oppositedirections. The magnetic head base 62 descends, guided by the positionof the control cam grooves 102a, 102b, 104a, 104b in the portion labeledB4 in FIG. 19. The magnetic head base 62 passes the standby position,descending towards the magnetic head application position P4. In thisinterval, the first loading sensor 326 detects a momentary ON(approximately 20 ms) as the gap 322a in the first encoder rib passesthrough the sensor 326; this momentary ON is ignored by the controlcircuit. Also in this interval, the draw-in sensor 260 is turned ON asthe follower pin 262 is slightly pushed clockwise by the edge of thelink arm 284. As the magnetic head base 62 continues to descend, itreaches the horizontal portion B5 at position P4 of the control camgrooves 102c, 102d, 104c, and 104d. FIGS. 39, 47, 48, and 55 show top,left, right and front plan views of the status of the cartridge loadingsystem 52 and other mechanisms in the magnetic head application positionP4, with the magnetic head 14 "flying" on the surface of the disk 12 andin position to commence a writing operation. FIG. 64(e) is a detailedplan view of the timing control system 60 at position P4. As the linkarm 184 continues in the clockwise direction, the upright projection312c of the catch arm 312 abuts the cocking axis pin 302, and the catcharm is forced in the counterclockwise direction, releasing the drivingpin 298, as shown in FIG. 64(e). Simultaneously, thecounterclockwise-biased locking arm 300 has swung andelectromagnetically locked to the electromagnet 290 as the driving pin298 enters the concave stopper 300b. Thus, the electromagnetic fail-safemechanism is "cocked", and the driving pin 298 is held by the concavestopper 300b as long as the electromagnet 290 is energized. At thispoint, the first encoder rib 322 passes out of the detection gap of thefirst loading sensor 326, turning the sensor 326 ON. The motor 56 isstopped at this point, and the magnetic head base 62 is stopped and heldin the magnetic head application position P4.

The unloading operation is the reverse of the loading operation, withsome significant differences hereafter described. The timing of theunloading operation is shown in FIGS. 59 and 60. The status of thecartridge loading system 52 and timing control system 60 may be followedin reverse order in FIGS. 55 through 36 and 64(e) through 64(a)respectively.

When the control circuit determines that the magnetic head 14 is to beremoved, the control cam plates 102 and 104 must be reversed from themagnetic head application position P4 to the cartridge loaded positionP3, and the motor 56 is started in the reverse (unloading) direction. Inthis reverse operation, the gear arm 310 starts moving in thecounterclockwise direction, and the sensors 260 and 326 are again turnedON. As the encoder cam gear 324 rotates, the concave catch 312b of thecatch arm 312 re-engages the driving pin 298 as the concave stopper 300bof the locking arm 300 is forced away at the corner of the concavestopper 300b. At this point, the first encoder rib gap 322a passesthrough the first loading sensor 326, generating an ON signal that tellsthe control circuit to de-energize the electromagnet 290. Thus, theelectromagnetic fail-safe mechanism is "uncocked", and the link arm 284again moves together with the gear arm 310. The link arm 284 and thegear arm 310 then move together back to the cartridge loaded position P3(in this case, the same as the standby position) where the secondencoder rib 324 passes out of the detection gap of the second loadingsensor 328 and generates an ON signal to the control circuit. Here, thecontrol circuit stops the motor 56.

The timing from the cartridge loaded position P3, through the cartridgedrawn-in position P2, to the cartridge insertion (in this case,ejection) position P1 is shown in FIG. 60. When the control circuitdetermines that the cartridge 42 is to be ejected, the motor 56 is againstarted in the reverse (unloading) direction. The cartridge holder isguided up to the cartridge drawn-in position P2. At this point, theslide plate 268 and hook lever 274, driven by the draw-in link member266 and encoder cam gear 234, begins to push the cartridge 42 from thedrawn-in position P2 inside the cartridge holder 100 to the insertionposition P1. As the encoder cam gear 234 continues to rotate in thereverse direction, the interruptor member 250a passes out of thedetection gap of the draw-in sensor 260, but the resultant ON signal isnot used by the control circuit. The control circuit determines that thedisk cartridge 42 is brought back to the cartridge insertion position P1when first encoder rib 322 passes out of the detection range of thefirst loading sensor 326, and stops the motor 56 at this point.

The timing of the automatic cartridge loading system 42 is againdifferent when the electromagnetic fail-safe mechanism 288 has beenactuated by a loss of power when the magnetic head base 62 is in theapplied position (corresponding to control cam plate 102 and 104magnetic head application position P4). The fail-safe mechanism sendsthe cartridge loading system 52 to the position P5 shown in plan, left,and right views in FIGS. 40, 49, and 50 respectively. The status of thetiming control system 60 is shown in FIG. 65. FIG. 61 shows the timingof the sensor and signal status following a power loss, the dotted linerepresenting a power loss. As previously described, when power is lost,the armature contact 300a is released from the electromagnet 290, theconcave stopper 300b releases the axis pin 298, and the link arm 284 andcontrol cam plates 102 and 104 return to the standby position (close tocartridge loaded position P3) under the bias of the return spring 318,moving the magnetic head 14 and magnetic head base 62 away from the disk12.

When the link arm 284 returns to the standby position, the encoder camgear 234 does not rotate, and the status of the loading sensors 326 and328 remains unchanged at ON and OFF respectively, while the draw-insensor 260 is again blocked by the interruptor member 250a as the linkarm 284 returns. FIG. 65 shows the status of the timing control system60 after an actuation electromagnetic fail-safe mechanism 288. At thispoint, when power is returned, the control circuit performs a restartoperation.

The control circuit recognizes that a restart operation must beperformed by the ON, OFF, and ON status of the loading sensors 326 and328 and the draw-in sensor 260 respectively. The control circuit thenstarts the driving motor 56 in a reverse (unloading) direction as shownin FIG. 62, and starts the spindle motor 44 to spin the disk 12. Thelink arm 284 is not coupled to the gear arm 310 at this point and doesnot rotate. However, as the encoder cam gear 234 rotates, the gear arm310 swings counterclockwise.

The first encoder rib 322 then enters the detection gap of the firstloading sensor 326, turning OFF the sensor 326, followed by a short ONsignal as the first encoder rib gap 322a enters the detection area offirst loading sensor 326. These signals from the sensor 326 are ignoredby the control circuit. Further rotation of the encoder cam gear 234allows the concave catch 312b of the clockwise-biased catch arm 312 tore-engage the axis pin 298 of the link arm 284, and then advances thesecond encoder rib 324 out of the second loading sensor 328, generatingan ON signal. This ON signal from the second loading sensor 326signifies that the encoder cam gear is at the standby position, and themotor 56 is stopped.

When the control circuit determines that the magnetic head 14 is to beapplied, the electromagnet 290 is energized, and the motor 56 againdrives the encoder cam gear 234 in the forward (loading) direction (asshown in FIG. 63), moving the gear arm 310 and the link arm 284 in theclockwise direction, and the control cam plates 102 and 104 in theloading direction. The forward rotation of the encoder cam gear 234causes, in order, an OFF signal of the second loading sensor 328, an OFFsignal of the draw-in sensor 260, and a momentary ON signal of the firstloading sensor 326, all of which are ignored by the control circuit. Themagnetic head base 62 descends, guided by the control cam plates 102 and104 as these signals are generated. As the rotation of the encoder camgear 234 continues, when the magnetic head base 62 reaches the magnetichead application position P4, the first encoder rib 322 passes out ofthe detection range of the first loading sensor, generating an ONsignal. The control circuit turns off the motor 56 upon receiving thisON signal from the first loading sensor 326, and the magnetic head 14 isin the writing position.

Thus, the timing control system 60 is able to load and unload acartridge 42 and apply and remove a magnetic head in all operatingcircumstances without the use of many sensors or a complicatedelectronic control circuit. Furthermore, the timing control system 60uses very few parts, and at least the cam encoder gear 234 and controlcam plates 102 and 104 are unitarily formed, and each serves multipledriving, guiding, and/or sensing functions.

(e) Shutter Operating Mechanism 40

An embodiment of a shutter operating mechanism according to theinvention is shown in FIGS. 66 through 75. The shutter operatingmechanism moves a shutter blade 38 in synchronization with cartridgeloading and unloading events as previously described, completelyretracting the shutter blade 38 from the cartridge loading path andcompletely covering the cartridge insertion slot 34 both when the diskdrive 10 is empty and when a cartridge 42 is loaded.

As shown in FIGS. 66 and 67, the shutter operating mechanism 40comprises a shutter blade 38 and left and right swinging levers 212 and210. The shutter blade 38 is swingably supported at the distal ends ofthe swinging levers 212 and 210. The left and right swinging levers 212and 210 are swingably supported by left and right pin axes 208 and 206on the respective sides plates 26e and 26d of the loading chassis 26.Torsion springs 220 and 218, provided to the pin axes 208 and 206, biasthe swinging levers to swing downwards. The swinging levers 212 and 210further comprise cam pins 216 and 214, projecting outwards from therespective swinging levers 212 and 210 at the approximate middleportions of the levers 212 and 210. The left and right cam pins 216 and214 mate with respective cam grooves 101a and 101b of the correspondingcam plates 102 and 104, and the motion of the swinging levers 212 and210 is thereby defined by the profile and movement of the cam grooves101a and 101b.

A sector gear 224 is rotatably mounted to an axis pin 222 provided tothe front end of the swinging lever 210, near to the shutter blade 38.The sector gear 224 comprises a unitarily formed stopper 230, thestopper 230 positioned on the opposite side of the axis pin 222, and thestopper 230 is able to turn the sector gear 224 so that the sector gear224 rotates upwards when the stopper 230 is rotated downwards. Thesector gear 224 is biased to turn down by a torsion spring 228 providedto the axis pin 222. The sector gear 224 engages with a shutter bladegear 226, formed unitarily with the shutter blade 38. When the sectorgear 224 turns up, the shutter blade gear 226 swings the rotatablymounted shutter blade 38 towards an open state. The sector gear 224turns up when the stopper 230 is turned down by contact with a contactplate 118c on the right side plate 118a of the gear chassis 118,according to the motion of the right control cam plate 104 and the camgroove 101b.

The operational positions and steps of the shutter operating mechanism40 appear in FIGS. 68 to 75. The operation of the shutter operatingmechanism 40 is shown by only the right swinging lever 210, right campin 214, and right control cam plate 104, although the left swinginglever 212 follows a symmetrically equivalent path as it is guided by theleft control cam plate 102.

As shown in FIG. 68, when a disc cartridge 42 is not loaded in the diskdrive 10, the right cam pin 214, controlling the movement of the rightswinging lever 210, contacts the right cam groove 101b at the firsthorizontal portion C1, defining the lowest position of the rightswinging lever 210. The symmetrical left side parts are similarlypositioned. At this point, nothing contacts the stopper 230, and theshutter blade 38 is in the closed position by virtue of the bias of thetorsion spring 228. As the front of a disk cartridge 42 is inserted intothe chassis opening 36 of the disk drive 10 as shown in FIGS. 69 and 70,the shutter blade 38 is pushed by the front end of the disk cartridge42, and rotates inward. The inward rotation of the shutter blade 38turns the shutter blade gear 226, turning the sector gear 224 againstthe bias of the torsion spring 228. The swinging levers 210 and 212remain at their lowest positions.

As the cartridge 42 proceeds to the position shown in FIG. 71, theautomatic cartridge loading system 52 is activated, and moves thecontrol cams 102 and 104. The surface C2 of cam groove 101b lifts thecam pin 214, and the swinging lever 210 is moved up, bringing theshutter plate 38 up, as shown in FIG. 72. On the left side, the controlcam plate 102, cam groove 101a and cam pin 216 are symmetrically engagedand in motion. Before the cam pin 214 reaches its highest position, thestopper 230 contacts the bottom of the contact plate 118c of the gearchassis 118, swinging the sector gear 224 up. As the cartridge 42 isdrawn fully into the cartridge holder 100 by the automatic cartridgeloading mechanism 52, the cam plates 102 and 104 continue, and the camgroove 104 guides the cam pin 214 to position C3, the highest positionof the pin 214 and swinging lever 210 (FIG. 73). At this point thestopper 230 has swung the sector gear 224 and the shutter blade 38 upand away from the cartridge 42. As the control cam plates 102 and 104are later moved in an opposite direction to eject a cartridge 42, andthe shutter blade 38 must be moved to an open position when thecartridge 42 is ejected, moving the shutter blade 38 up and away at thedescribed point on the cam surface 101b serves to keep the shutter blade38 from interfering with the cartridge 42 during the ejection operation.

After the cartridge 42 is completely drawn into the cartridge holder100, the control cam plates 102 and 104 then continue into the stateshown in FIG. 74. The right cam pin 214 follows the downwardly inclinedsurface C4 of the groove 101b (corresponding to movements of the pin 216and groove 101a on the left side), and the swinging lever 210 swingsdown. At the same time, the stopper 230 moves away from the contactplate 18c, and the shutter blade 38 is returned to a vertical position.As the control cam plate 104 moves into the state shown in FIG. 75, thecam pin 214 engages the horizontal surface C5 of the cam groove 101b,and the shutter blade 38 closes the chassis opening 36 similarly to thebeginning of the operation, but with the cartridge 42 and the cartridgeholder 100 completely drawn into the disk drive 10 housing.

When the disk cartridge 42 is ejected, the control cam plates 102 and104 move in opposite directions, and the shutter operating mechanism 40operates in the reverse order to that described.

Thus, the shutter blade 28 closes the chassis opening 36 at all times,except during actual cartridge insertion or ejection. According to thedescribed embodiment of a shutter operating mechanism 40, the shutterblade 38 is resiliently pressed against the inside surface of the frontpanel 26a of the loading chassis 26 by the bias of the torsion spring228. Both swinging levers 210 and 212 are further resiliently presseddownward by the bias of the torsion springs 218 and 220. Consequently,if a foreign object is inserted into the chassis opening 36 during thecartridge loading operation, the shutter blade 38 and swinging levers210 and 212 will resiliently give, and the shutter operating mechanism40 is not damaged or jammed by any outside influence.

(f) Magnetic Head Vertical Positioning System 64

The magnetic head base 62 is precisely vertically positioned withrespect to the mounting base 24 by means of a resilient four-pointvertical positioning system 64. The positioning system comprises rightand left position determining fixtures 24a and 24b, mounted to posts atthe rear of the mounting base 24 as shown in FIG. 8. The right and leftposition determining fixtures 24a, 24b have accurately machined topreference surfaces and cylindrical sockets 332a, 332b and are formed ascylindrical pin-socket members, the pin portions fitting into holes (notshown) on the posts of the mounting base 24. Alternatively, the topreference surfaces of the fixtures 24a, 24b and cylindrical sockets332a, 332b may be unitarily formed with the mounting base 24.

The vertical positioning system 64 further comprises the referencesurface tabs 26f and 26g of the loading chassis 26, which providereference surfaces towards the front of the magnetic head base 62, asshown in FIGS. 20 and 79. Lastly, the vertical positioning system 64comprises the resilient pressure members 200a, 200b, 201a, and 201b, andthe wire springs 202 and 204, shown in FIGS. 15 through 18.

When the cam pins 178a, 178b, 179a, and 179b of the magnetic head base62 reach the horizontal portion B5 of the cam grooves 103a, 103b, 105a,and 105b respectively, the front and rear of the magnetic head base 62contact the reference surfaces. The front end edge of the magnetic headbase 62 abuts the reference surfaces 26f and 26g, and the rear endsurface of the magnetic head base abuts the top reference surfaces ofthe fixtures 24a and 24b. At this point, the cam pins 178a, 178b, 179a,and 179b are slightly lifted from the horizontal portion B5, and pushagainst the resilient pressure members 200a, 200b, 201a, and 201brespectively at the positions shown in FIGS. 47 and 48. Thus, themagnetic head base is dynamically and resiliently held against thereference surfaces 26f and 26g and the top reference surfaces of thefixtures 24a and 24b.

Thus, the dynamic four-point vertical positioning system 64 holds themagnetic head base 62 in a precise position with respect to the mountingbase 24, and therefore with respect to the optical head 16. Furthermore,the magnetic head base is resiliently biased against reference surfaces,and is therefore more stable and less subject to misalignment.

(g) Magnetic Head Horizontal Positioning System 66

FIGS. 76 through 79 show an embodiment of a magnetic head horizontalpositioning system 66 according to the invention. The horizontalpositioning system 66 properly and precisely positions the magnetic headbase 63 in the horizontal plane.

The left and right position determining fixtures 24a and 24b, mounteddirectly to the mounting base 24, have cylindrical position determiningsockets 332a and 332b respectively, as shown in FIG. 76. The taperedposition determining pins 334a and 334b of the magnetic head base 62 arepositioned to engage with sockets 332a and 332b of the positiondetermining fixtures 24a and 24b respectively when the magnetic headbase 62 is in the magnetic head application position P4. The matchingpins 334a, 334b and sockets 332a, 332b are constructed such that the fitbetween left pin 334a and socket 332a is a clearance fit (allowing somehorizontal relative movement), and the fit between the right pin 334aand socket 332b is a slip fit (no horizontal relative movement). FIG. 77shows a bottom plan view of the fitted fixtures 24a, 24b and pins 334a,334b.

The magnetic head horizontal positioning system 66 is shown in FIG.78(a) and 78(b), and comprises a pre-load link arm 338, a pre-load slideplate 340, a pre-load arm 344, and a pre-load spring 346. The L-shapedpre-load link arm 338 is rotatably supported at the elbow of the L shapeby an axis pin 26b fixed to the left side 26b of the loading chassis 26,and may rotate in a vertical plane. The pre-load link arm 338 comprisesa cam follower pin 348 on an arm of the L shape, and the cam followerpin 348 extends to the control cam plate 102 and is guided by thepre-load cam groove 113a formed in the plate 102. The pre-load link arm338 further comprises a pusher pin 350, fixedly mounted to the remainingarm of the L shape, and the pusher pin 350 extends below the magnetichead base 62 to push the slide plate 340 when the magnetic head base isin the magnetic head application position P4. The pre-load slide plate340 is slidably mounted to the bottom of the magnetic head base 62, andthe pre-load slide plate 340 slides in the direction X (FIG. 78(b), FIG.79) when pushed by a pusher pin 350 attached to the pre-load link arm338. The L-shaped pre-load arm 344 is rotatably mounted to the bottom ofthe magnetic head base at the elbow of the L shape, rotating in ahorizontal plane about an axis pin 342 fixed to the bottom of themagnetic head base 62. The pre-load arm 344 comprises a vertical contactportion 352 on a rear arm 344a of the L shape, and the arm 344 canrotate slightly such that the vertical contact portion 352 contacts theposition determining fixture 24a when the magnetic head base is in themagnetic head application position P4. The pre-load spring 346 isstretched between a tab 344c on a transverse arm 344b of the L-shapedpre-load arm 344 and a tab 340a on the pre-load slide plate 340, and thespring 346 biases the slide plate 340 towards the back of the magnetichead base 62. When the slide plate 340 is not pushed by the pusher pin350, the vertical contact portion 352 of the pre-load arm has a slightclearance with the position determining fixture 24a, as shown in FIG.78(a). When the slide plate 340 is pushed, the vertical contact portion352 is brought to contact the position determining fixture 24a as thepre-load arm is swung by the pre-load spring 240, as shown in FIG.78(b).

As shown in FIG. 79, when the control cam plate 102 reaches the magnetichead application position P4, the pre-load link arm 338 rotatesclockwise (from the perspective of FIG. 79), guided by the pre-load camgroove 113a and the cam follower pin 348, from the position shown by asolid line in FIG. 79 to the position shown by a double-dotted line inFIG. 79. At this point, the pusher pin 350 pushes the pre-load slideplate 340 in the direction opposite to the loading direction X againstthe bias of the pre-load spring 346. The pre-load spring 346 rotates thepre-load arm 344 so that the vertical contact portion 352 moves towardsthe position determining fixture 24a and contacts the outercircumference of the fixture 24a. At this point, the magnetic head base62 is pushed at the vertical contact portion 352, and slightly rotatesabout the slip fit between the right position determining pin 334b andsocket 332b of position determining fixture 24, such that thecylindrical wall of the left position determining fixture 24a isresiliently clamped between the vertical contact portion 352 and theleft position determining pin 334a, as shown in FIG. 78(b). The magnetichead base 62 is thus precisely positioned and immobilized in thehorizontal plane by the horizontal positioning system 66, by virtue ofthe initial restriction to a single rotational degree of freedom in ahorizontal plane, and then the removal of all horizontal freedom ofmovement with a resilient bias against a reference surface.

(h) Magnetic Head Carriage Lock Mechanism 70

When the linear motor 162 that moves the magnetic head carriage 68 isunpowered, the magnetic head carriage 68 is free to slide back and forthalong the linear bearing 156 if it is not restrained. An embodiment of amechanism 70 for locking the magnetic head carriage 68 in the "idle"position, according to the invention, appears in FIGS. 80 to 83.

The magnetic head carriage lock mechanism 70, shown in detail in FIGS.82 and 83, comprises a lock lever 356, positioned to engage the L-shapedstopper hook 354 of the magnetic head carriage 68. The lock lever 356 issubstantially L-shaped with one arm of the L shape pointing downwards,and is rotatably mounted to a lock mount 358. The lock mount 358 isfixed to the upper part of the inner wall of the rear cover 30. The lockmount comprises a mounting stay 360, two vertical fixture portions 362a,362b, a shaft 364, and a torsion spring 366. The mounting stay 360 isdirectly attached to the rear cover 30, and the vertical fixtureportions 362a, 362b are parallel and project downwards. The shaft 360 isfixed between the two fixture portions 362a, 362b, transverse to theloading direction X. The lock lever 356 is rotatably mounted to theshaft 360, and the torsion spring 366 is provided to the shaft 360 andbiases the lock lever 356 in a clockwise direction (as seen in FIG. 83).When not engaged, the lock lever 356 is held with the upper arm of the Lshape horizontal by a front edge portion of the mounting stay 360.

When the control circuit of the disk drive 10 determines that themagnetic head 14 is to be removed from the disk 12 (for example, at theposition shown in FIG. 80), it controls the motor 56 to move themagnetic head base 62 to the "standby" position. In the "standby"position, the control circuit momentarily pauses the ascent of themagnetic head base 62. At this point, the linear motor 162 transfers themagnetic head carriage 68 towards the outer edge of the disk 12 until itreaches a mechanical stop, as shown in FIG. 81. Then, if the magnetichead base 62 is to be moved to the insertion position P1 or cartridgedrawn-in position P2 (both of which are "idle" positions of the magnetichead base 62), the motor 56 is restarted and the magnetic head basecontinues to its topmost position (with the head carriage 68 held at theoutermost position). As the magnetic head base 62 is moved to the "idle"position, the stopper hook 354 provided to the carriage arm 170 of themagnetic head carriage 68 engages with the spring-loaded lock lever 356.At this point, the magnetic head carriage 68 can only be released fromthe lock mechanism 70 to move horizontally if the magnetic head base 62is moved back down by the control circuit. Thus, even if power to thedisk drive 10 is removed, the magnetic head carriage 68 remainsrestrained from movement.

Thus, as a linear motor conventionally allows free movement whenunpowered, the magnetic head carriage lock mechanism 70 immobilizes themagnetic head carriage 68 when the disk drive 10 is transported or idle.The sensitive magnetic head 14 is thereby protected from shock damageand misalignment.

(i) Head Synchronization Control System

In order to synchronize reading and writing operations of the MO diskdrive 10, the magnetic head 14 and the optical head 16 must bedynamically aligned with each other. An embodiment of a magnetic headand optical head synchronization process performed by the controlcircuit is described in flow charts in FIGS. 84 through 87. FIG. 84 is amaster flow chart for the entire process, and FIGS. 85 through 87describe synchronization subroutines when the magnetic head 14 isapplied to an removed from the disk. The system optimizes thesynchronization process by aligning the magnetic head 14 and opticalhead 16 to each other early on, thus saving time later when the linearpositions of the heads 14 and 16 are synchronized.

The process begins when the control circuit checks if the power isapplied (step S10), and proceeds when the power is ON. A sensor check isthen performed, where the control circuit checks the first and secondloading sensors 326 and 328 and the cartridge draw-in sensor 260 (S12).If the sensors 326, 328, and 260 are ON, OFF and OFF respectively atstep S12, the control circuit interprets these signals to mean that theelectromagnetic fail-safe mechanism 288 has been released and themagnetic head base 62 has been moved to the "standby" position, andproceeds to step 24. If all the sensors 326, 328, 260 are ON, thecontrol circuit interprets these signals to mean that the cartridgeholder 100 and disk cartridge 42 are in the cartridge insertion positionP1, and proceeds to step 14. If the sensors 326, 328, and 260 are not ineither of the states described above at step S12, then the controlcircuit proceeds immediately to the cartridge ejection process (S22) andejects any inserted cartridge 42 from the disk drive.

At step 14, the control circuit loops until the cartridge draw-in sensor260 is OFF, signaling that a cartridge 42 has been inserted and pushedinto the holder 100. The cartridge loading process (S16) is then started(described below and detailed in FIGS. 85 and 86), and after thecartridge is loaded to a reading or writing position, the controlcircuit begins a reading or writing process (S18). The reading orwriting process continues until an eject switch 386 (see FIG. 1) isactuated (S20), whereupon the cartridge ejection process is performed(S22, described in detail below and shown in FIG. 87).

At step 24, the control circuit returns the encoder cam gear 324 to the"standby" position. The process flow then proceeds to the magnetic headre-application process (S26) to re-apply the magnetic head 14 to thedisk 12, and returns to the main flow at the reading or writing process(S18).

The cartridge/magnetic head loading process (S16) is shown in detail inFIGS. 85 and 86. In this process, the motor 56 is driven in the forward(loading) rotation (S16A) until the second loading sensor 328 turns OFF(S16B) and the motor is stopped. These steps (S16A, S16B, S16C) resultin the cartridge 42 being drawn in to the cartridge holder 100 and movedto the cartridge loaded position P3, and the magnetic head base 62 ismoved to the "standby" position. In the cartridge loaded position P3,the disk 12 may be read by the optical head 16. The control circuit thenchecks a write protect sensor (not shown) and assigns 1 to the writeprotect flag (FWP) if the cartridge 42 is write protected, and 0 to FWPif the cartridge 42 is not write protected (S16D, S16E, S16F). Thecontrol circuit then rotates the spindle motor (S16G) at the ECMAstandard operating speed 3000 rpm and actuates the linear motor 134 tomove the optical head 16 to the innermost position (S16H). At thisposition, the optical reads the disk format information PEP (S16I) andraises the spindle motor 44 speed to 4000 rpm if the disk 12 is an ISOstandard disk (S16J, S16K).

The control circuit then checks the write protect flag FWP in step S16L,and if the disk is write protected (FWP=1), the magnetic head 14 willnot be used and the control flow returns directly to the main routine ofFIG. 84. If the disk 12 is not write protected (FWP=0), the controlcircuit moves the magnetic head carriage 68 to the outermost position(S16M) and the optical head carriage 128 to the MFZ reading position(outermost position) at step S16N, and reads the manufacturer'sformatting zone MFZ using the optical head 16 on the optical headcarriage 128 to determine if the inserted disk 12 is single ordouble-sided (S16O, S16P). The MFZ reading position of the optical head16 corresponds to the outermost position of the optical head 16, and isslightly inside the outermost position of the magnetic head 14. If thedisk 12 is double-sided, the magnetic head 14 will not be used and thecontrol flow returns directly to the main routine of FIG. 84.

If the disk is single-sided, the control circuit energizes the fail-safeelectromagnet 290 (S16Q), and starts the motor 56, driving the motor 56until the first loading sensor stays ON for more than 20 ms (S16R,S16S). These steps (S16Q, S16R, S16S) bring the magnetic head base 63down to the magnetic head application position P4 where the magnetichead 14 may "fly" above the disk 12, and the magnetic head base 62 iselectromagnetically held in position.

At this point, the control circuit moves the magnetic head carriage 68to synchronize the radial positions of the optical and magnetic heads 14and 16 (S16U), using the reflector plate 154 on the optical carriage arm154 and the photocouplers 150 and 152 on the magnetic head carriage arm170. As both the magnetic head 14 and the optical head 16 are already attheir outermost positions, the synchronizing time is very short.Alternatively, the magnetic head 14 is first brought inwards to aposition corresponding to the MFZ reading position (the outermostposition) of the optical head to further speed the synchronizationprocess. At this point, the control circuit returns to the main processof FIG. 84.

The unloading process of step S22 appears in detail in FIG. 87. When theunloading process of step S22 is called, the control circuit rotates themotor 56 in a reverse direction until both the first and second loadingsensors 326, 328 are ON, de-energizing the electromagnet 290 when thefirst loading sensor 326 is detected as ON and stopping the drive motor56 and turning OFF the spindle motor 44 when the second loading sensor328 is detected as ON (S22A through S22F). In this case, the ONdetection of the first detecting sensor 326 is caused by the firstdetection rib gap 322A. In these steps (S22A through S22F), the magnetichead base 62 is brought from the magnetic head application position P4to the "standby" position (corresponding to the cartridge loadedposition P3). The spindle motor 44 slows down gradually when turned OFFin step S22F by virtue of the rotational inertia of the loaded disk 12.The control circuit then activates the linear motor 162 to move themagnetic head carriage 68 to the outermost radial position (S22G), andwaits for the spindle motor to stop (S22H).

The driving motor 56 is re-activated in the reverse (unloading)direction until the first loading sensor 326 is detected as ON, wherethe motor 56 is stopped (S22I, S22J, S22K). These steps (S22, S22J,S22K) move the cartridge holder to the topmost position and push thedisk cartridge 42 out to the cartridge insertion position P1, andfurther move the magnetic head base 62 to the topmost "idle" positionwhere the magnetic head carriage lock mechanism 70 engages andimmobilizes the magnetic head carriage 68. The disk cartridge 42 ispartially ejected through the front panel opening 34 at the cartridgeinsertion position P1, and may be easily extracted by hand. The controlcircuit then terminates the unloading process and returns to the mainprocess of FIG. 84.

As described, by this system, the control circuit is able to save timein the initialization process by ensuring that the magnetic 14 head andoptical head 16 are almost aligned before beginning any synchronizationprocess, and even before it is decided by the control circuit thatsynchronization is necessary.

(j) Beam Splitter Arrangement 74

An arrangement for a laser beam splitter 74 appears in detail in FIGS.92 and 93. The beam splitter arrangement 74 keeps all incident andexiting beams perpendicular or parallel to each other, while at the sametime reflecting stray light away from a laser source 370 and the signaldetector 376. A laser optical system 72 that directs a laser beam to theoptical head 16 is mounted at the back of the mounting base 24, as shownin FIGS. 36 and 41. Shown in detail in FIG. 92, the laser optical system72 comprises an optical housing 368 fixed to the mounting base 24 at thelaser optics reference plane Z. The optical housing 368 comprises asemiconductor laser source 370, a collimator lens 372 for converging thelaser beam from the laser 370, and a beam splitter 74. The laser beamfrom the semi-conductor laser source 370 follows the optical axis L0 (inan opposite direction along the L0 direction arrow to the directionshown in FIG. 92) and impinges on the beam splitter 74, where it isdivided into two beams, a first beam directed to the optical head 16 andthe disk 12 along an optical axis L1 and a second beam directed to apower controller photodiode 374 along an optical axis L2. Lightreflected from the disk 12 enters the optical head 16, and returns alongthe optical axis L1, striking the beam splitter 74, and then isinternally reflected in the beam splitter 74 to a condenser lens 378along an optical axis L3. The condenser lens 378 converges the beamalong the optical axis L3, and the converged beam proceeds to apolarizing splitter 380 where it is split into so-called s and ppolarized light beams, the s and p polarized beams sent on to a signaldetector 376.

The beam splitter 74 is formed by cementing a dielectricsemi-transmissive layer and two triangular prisms 382 and 384 by knownoptical cementing techniques. The first triangular prism 382 comprisestwo right angle surfaces 382a and 382b, at right angles to each other,and a hypotenuse surface 382c as shown in FIG. 93. The second triangularprism 384 also comprises two right angle surfaces 384a and 384b, atright angles to each other, and a hypotenuse surface 384c. The beamsplitter 74 is formed by cementing the hypotenuse surface 384c of thesecond prism 384 to a right angle surface 382a of the first prism 382.The dielectric semi-transmissive mirror layer is formed between thecemented surfaces 382c and 384b.

To prevent stray light from returning to the semiconductor laser 370 orfrom striking the signal detector 376, the angles between reflective andtransmissive surfaces are predetermined to direct scattered light towardother directions. The angle between the right angle surface 382a and thehypotenuse (cemented) surface 382c of the first prism is 44 degrees, andthe angle between the right angle (cemented) surface 384b and thehypotenuse surface 384c is 44 degrees. The beam splitter is arrangedsuch that a normal line N1 to the surface 382a of the first prism 382 isinclined by 1.51 degrees to the optical axis L0. If an optical mediumhaving a refractive index of 1.51 is used for the prisms 382 and 384,the angle between the optical axis L0' (refracted beam entering theprism) and the normal line N1 becomes 1 degree. Consequently, both theangle of incident light along optical axis L0' upon thesemi-transmissive prism surface 384b and the angle of reflected lightfrom the semi-transmissive surface 384b along optical axis L1' are 45degrees. The optical axis L1' is inclined by 1 degree from the normal N2to the surface 382b, and the exit optical axis L1 is inclined by 1.51degrees from the normal N2. Similarly, the exit optical axes L2 and L3from the hypotenuse surface 384c are each deflected from the normal N3or N4 to the surface by 1.51 degrees.

Accordingly, the optical axes L0 and L1 are maintained perpendicular toeach other, and the optical axes L2 and L3 are kept parallel,duplicating the axis relationships of a conventional beam splitter madewith two cemented isosceles triangle sided prisms. However, by incliningthe optical axes to the normal lines of incident and exit surfaces, thereflected stray light at each surface follows a different path thanincident light. For example, stray light emitted by the semiconductorlaser source 370 and reflected by the hypotenuse surface 382a isreflected at an angle of 3.02 degrees and does not return to thesemiconductor laser source 370. Similarly, stray light reflected by thesemi-transmissive surface 384b to the right angle surface 382b isreflected from the surface 382b at a 2 degree angle within the prism,and does not fall upon either the semiconductor laser source 370 or uponthe signal detector 376.

Furthermore, the semi-transmissive dielectric mirror surface of a beamsplitter must be redesigned when the angle of incident light changes. Inthe described beam splitter structure 74, the angle of incident light onthe semi-transmissive mirror surface is always 45 degrees. Since the 45degree angle is the same as conventional isosceles triangle prism beamsplitters, the semi-transmissive dielectric mirror layer does notrequire redesign.

The present disclosure relates to subject matter contained in JapanesePatent Application Nos. HEI 5-300868, HEI 5-300869, HEI 5-300870, HEI5-300871, HEI 5-300872, HEI 5-300873 and HEI 5-300875, all filed on Nov.6, 1993, which are expressly incorporated herein by reference in theirentireties.

What is claimed is:
 1. A shutter operating mechanism for a diskcartridge insertion opening of a disk drive, said mechanism comprising:amovable member; a shutter plate pivotably supported about a movable axison said movable member, said movable axis and said shutter plate beingmoved by said movable member between a closed position and a retractedposition, said closed position being defined by said shutter plate fullyclosing said cartridge insertion opening, and said retracted positionbeing defined by said shutter plate being pivoted about said movableaxis away from a loading path of an inserted cartridge while saidmovable axis of said shutter plate is retracted away from said loadingpath of an inserted cartridge; and a moving mechanism for moving saidmovable member, said movable axis, and said shutter plate between saidclosed and retracted positions.
 2. The shutter operating mechanismaccording to claim 1,wherein said movement of said moving mechanism issynchronized with a disk cartridge loading mechanism of said disk driveby a synchronizing member.
 3. The shutter operating mechanism accordingto claim 1,wherein said first position of said moving mechanismcorresponds to a position of a disk cartridge loading mechanism where adisk cartridge holder of said disk cartridge loading mechanism is empty,and wherein said second position of said moving mechanism corresponds toa position of said disk cartridge loading mechanism where said diskcartridge is lowered in said disk cartridge holder to said spindle motorof said disk drive.
 4. The shutter operating mechanism according toclaim 1, further comprising a chassis, said moving mechanism including:afirst guide element on said chassis, said guide element including first,second and third distinct positions, said movable member beingoperatively connected to said shutter plate and being guided by saidfirst guide element, said first guide element and said movable memberguiding said movable member, said movable axis, and said shutter plateto said closed position at said first position, to said retractedposition at said second position, and back to said closed position atsaid third position.
 5. The shutter operating mechanism according toclaim 4, said first guide element being a cam plate.
 6. The shuttermechanism according to claim 4, further comprising said movable memberpivotally connected to said chassis, said shutter plate being pivotallyconnected to said movable member, and said moving mechanism moving saidmovable member and said shutter plate away from said loading path ofsaid inserted cartridge.
 7. The shutter operating mechanism according toclaim 6, said second guide element being operatively attached to said atleast one lever.
 8. The shutter mechanism according to claim 6, saidmovable member comprising a lever.
 9. The shutter operating mechanismaccording to claim 6, further comprising an actuator mechanism formoving said shutter plate with respect to said at least one leverbetween said closed position and said retracted position.
 10. Theshutter operating mechanism according to claim 9, said actuatormechanism including a stopper, said stopper being arranged to stop thefree swinging of said shutter plate when said moving mechanism is insaid second position.
 11. The shutter operating mechanism according toclaim 9, said actuator mechanism including a first gear on said at leastone lever and a second gear on said shutter plate, said first and secondgear cooperating with each other to move said shutter plate.
 12. Theshutter operating mechanism according to claim 9, further comprising astopper connected to one of said first and second gears, said stopperbeing arranged to stop the free swinging of said shutter plate when saidmoving mechanism is in said second position.
 13. A shutter operatingmechanism for a disk cartridge insertion opening of a disk drive, saidmechanism comprising:a movable member; a shutter plate pivotablysupported about a movable axis on said movable member, said movable axisand said shutter plate being moved by said movable member between aclosed position and a retracted position, said closed position beingdefined by said shutter plate fully closing said cartridge insertionopening, and said retracted position being defined by said shutter platebeing pivoted about said movable axis away from a loading path of aninserted cartridge while said movable axis is retracted away from saidloading path of an inserted cartridge; and a moving mechanism for movingsaid movable member, said movable axis, and said shutter plate betweensaid closed and retracted positions, said moving mechanism guiding saidmovable member, said movable axis, and said shutter plate to said closedposition at a first distinct position, to said retracted position at asecond distinct position, and back to said closed position at a thirddistinct position.
 14. A shutter operating mechanism for a diskcartridge insertion opening of a disk drive, said mechanism comprising:achassis; a cam plate on said chassis, said cam plate including first,second and third guide positions; a shutter plate having a closedposition and a retracted position, said closed position being defined bysaid shutter plate fully closing said cartridge insertion opening, andsaid retracted position being defined by said shutter plate beingretracted from a loading path of an inserted cartridge; a guide elementguided by said cam plate, said guide element being operatively connectedto said shutter plate, said cam plate and said guide element incombination moving said shutter plate to said closed position at saidfirst guide position, to said retracted position at said second guideposition, and back to said closed position at said third guide position;and a moving mechanism for moving said cam plate, and thereby said guideelement and said shutter plate, said moving mechanism being movablebetween first, second, and third distinct positions at which said camplate is moved to said first, second, and third guide positions,respectively.